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Scoop
5 days ago
- Climate
- Scoop
NIWA Releases Seasonal Climate Outlook – June To August 2025
Press Release – NIWA Air temperatures are expected to be above average across all New Zealand regions for this winter season, according to NIWA's Seasonal Climate Outlook for June – August 2025. While cold snaps and frost will occur, they are expected to be less frequent than usual, says NIWA Principal Scientist Chris Brandolino. Rainfall totals during the three months ahead are expected to be above normal for the north of the North Island and near normal for the east of the South Island. For all remaining regions of the country, rainfall is forecast to be near normal or above normal. Higher than normal atmospheric pressure is expected to the east of the country, leading to north-easterly flow anomalies that may shift to a more north-westerly direction towards the end of the three-month period. Low pressure systems forming north of the country are still expected to affect New Zealand and may lead to heightened risks for heavy rainfall events. Outlook Summary Neutral El Niño – Southern Oscillation (ENSO) conditions remain present in the tropical Pacific. Residual signals indicative of weak La Niña conditions persist, and occasional La Niña-like atmospheric patterns may still emerge over the next three months International guidance indicates about a 70% chance for the tropical Pacific to remain in an ENSO-neutral state over the outlook period. For New Zealand, higher than normal atmospheric pressure is expected to the east of the country, leading to north-easterly flow anomalies that may shift to a more north-westerly direction towards the end of the three-month period. Low pressure systems forming north of the country are still expected to affect New Zealand and may lead to heightened risks for heavy rainfall events. Seasonal air temperatures are expected to be above average across all New Zealand regions for this winter season. Thus, while cold snaps and frost will occur, they are expected to be less frequent than usual. Sea surface temperatures (SSTs) remain well above average around most of New Zealand, except in offshore areas east of the North Island. In May, coastal SST anomalies ranged from +0.39°C to +1.47°C. Large regions offshore are currently experiencing Marine Heatwave (MHW) conditions. Global climate models suggest that SSTs in the New Zealand region are likely to stay above average over the next three months, although the intensity of the anomalies may ease. Monitor the SST update for updates. June – August rainfall totals are expected to be above normal for the north of the North Island and near normal for the east of the South Island. For all remaining regions of the country, rainfall is forecast to be near normal or above normal. Sub-seasonal, or monthly, projections of rainfall and dryness are updated daily through the NIWA35 forecast. During June – August 2025, near normal soil moisture levels and river flows are expected for all regions of the North Island, while near normal or above normal soil moisture levels and river flows are forecast for the South Island. Regional predictions for June – August 2025 The tables below show the probabilities (or percent chances) for each of three categories: above average, near average, and below average. In the absence of any forecast guidance there would be an equal likelihood (33% chance) of the outcome for any of the three categories. Forecast information from local and global guidance models is used to indicate the deviation from equal chance that is expected for the coming three-month period. All outlooks are for the three months averaged as a whole. During these three months, there will inevitably be relatively wet and dry periods, as well as hot and cold periods. The exact range in temperature and rainfall within each of the three categories varies with location and season. However, as a guide, the 'near average' or middle category for the temperature predictions includes deviations up to ±0.5°C relative to the long-term mean, whereas for rainfall the 'near normal' category lies between 80 percent and 120 percent of the long-term (1991-2020) mean. Northland, Auckland, Waikato, Bay of Plenty Temperatures are very likely to be above average (65% chance). Rainfall totals are most likely to be above normal (45% chance) for June – August 2025 as a whole, with occasional heavy rain events expected. Soil moisture levels and river flows are most likely (45-50% chance) to be near normal Central North Island, Taranaki, Whanganui, Manawatu, Wellington Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are about equally likely to be above normal (40% chance) or near normal (35% chance). Soil moisture levels and river flows are most likely (40-45% chance) to be near normal. Gisborne, Hawke's Bay, Wairarapa Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are most likely to be above average (45% chance). Rainfall totals are about equally likely to be near normal (40% chance) or above normal (35% chance). Soil moisture levels and river flows are most likely (45% chance) to be near normal. Tasman, Nelson, Marlborough, Buller Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are equally likely to be above normal (40% chance) or near normal (35% chance). Soil moisture levels and river flows are equally likely to be near normal (40% chance) or above normal (40% chance). West Coast, Southern Alps and foothills, inland Otago, Southland Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are about equally likely to be near normal (40% chance) or above normal (35% chance). Soil moisture levels and river flows are about equally likely to be near normal (40% chance) or above normal (35% chance). Coastal Canterbury and the nearby plains, east Otago Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are most likely to be in the near normal range (40% chance). Soil moisture levels and river flows are about equally likely to be near normal (40-45% chance) or above normal (35-40% chance). The full probability breakdown is: Graphical representation of the regional probabilities Background Sea surface temperatures (SSTs) anomalies in the central equatorial Pacific (Niño 3.4 Index) in May (values estimated using data to 26 May) are in the ENSO-Neutral range (-0.08C). SSTs currently are slightly below average in parts of the central Pacific, and cooler than average surface waters have re-emerged along the Equator east of about 120oW. The warmer than average ocean waters previously observed off the South American coast have dissipated. The relative Niño 3.4 Index (RONI*) for the past 30 days (to 26 May) was -0.47C, placing it on the La Niña side of neutral, indicating that ocean temperatures in the central and eastern Pacific remain cooler than the tropical average. As of 26 May 2025, the preliminary Southern Oscillation Index (SOI) value for May is +0.68, indicating conditions on the La Niña side of neutral. Atmospheric indicators – such as enhanced trade winds (positive zonal wind anomalies) and stronger-than-normal convective activity over the Maritime Continent – continue to reflect lingering influences from the previous La Niña event. In May 2025, upper-ocean heat content (temperature anomalies in the upper 300 metres of the ocean) remained above average across the western tropical Pacific, particularly west of approximately 170°W. Anomalies exceeding +2°C persisted south of the Equator, from the Maritime Continent to the International Dateline, near the latitude of the Solomon Islands. East of the Dateline, while isolated areas north and south of the Equator exhibited negative anomalies, heat content along the Equator itself was generally near average. This distribution is consistent with the tropical Pacific Ocean having transitioned away from La Niña conditions. In the subsurface equatorial Pacific, ocean temperatures remained significantly above average (anomalies > +3°C) between approximately 100- and 200-metres depth west of 170°W. Over the past week, these warm anomalies have expanded eastward and risen in the water column, with above-average temperatures now observed below roughly 50 metres depth west of about 130°W. In contrast, the central and eastern Pacific show limited cooler anomalies, with only a single isolated pocket of below-average temperatures near 50 metres depth off the South American coast. Taken together, these indicators suggest that the tropical Pacific ocean has largely transitioned away from La Niña conditions observed earlier this year. Notably, the previously prominent east–west gradient in heat content and subsurface temperature anomalies has diminished. Based on the dynamical and statistical models monitored by NIWA, ENSO-Neutral conditions remain the most likely outcome (73% chance) over the next three-month period (June – August 2025). However, intermittent weak La Niña-like atmospheric patterns may still occur over the winter season. For the remainder of the calendar year, ENSO-Neutral conditions are expected to persist. The guidance available however suggests the possibility for La Niña conditions to return by summer 2025 – 2026. The Southern Annular Mode (SAM) was mostly positive during the month of May (85% of days positive) and the monthly average anomaly was +0.5 std. A positive SAM index is typically associated with higher pressure than normal over New Zealand. Over the next two weeks, the SAM is forecast to become temporarily negative and then return to slightly positive values. The Indian Ocean Dipole (IOD) is currently in the neutral range, with the average anomaly for the month of May* 2025 being +0.36oC. The guidance from the Australian Bureau of Meteorology is for the IOD to remain in the neutral range until at least July after which it is forecast to become negative. During May 2025, intra-seasonal convective activity associated with the Madden-Julian-Oscillation (MJO) was generally weak, despite a temporary increase in MJO amplitude over the Maritime Continent mid-May. The MJO is likely to remain weak or indiscernible in the coming two-week period. Sea surface temperatures (SSTs) remain significantly higher than average around much of New Zealand. The exception is off the east coast of the North Island, where SSTs are currently near average. Marine Heatwave (MHW) conditions – defined as five or more consecutive days with SSTs above the 90th percentile – are ongoing along the west and southeast coasts of the South Island, as well as the west and northeast coasts of the North Island. SST forecasts for the June – August 2025 period suggest a slight weakening of these anomalies. However, above-average ocean temperatures are expected to persist around New Zealand through the winter season. *The Relative Oceanic Niño 3.4 Index (RONI) is a modern way of measuring oceanic El Niño and La Niña that is complementary to oceanic traditional indices. While traditional oceanic indices like the Niño 3.4 Index monitor SSTs in one region, the RONI compares the average SST in the central equatorial Pacific with the average SST across the global tropics. Since tropical rainfall patterns respond to changes in ocean temperatures, this new relative index can help forecasters better determine if the equatorial Pacific is warmer or cooler than the rest of the global tropics, which has become more challenging to discern as seas warm because of climate change. Forecast Confidence Notes: NIWA's outlooks indicate the likelihood of climate conditions being at, above, or below average for the season as a whole, relative to the 1991-2020 average. They are not 'weather forecasts' as it is not possible to forecast precise weather conditions three months in advance. The outlooks are the result of the expert judgment of NIWA's scientists and forecasters. They take into account observations of atmospheric and ocean conditions and output from global and local climate models. The presence of El Niño or La Niña conditions and the sea surface temperatures around New Zealand can be useful indicators of likely overall climate conditions for a season. The outlooks state the probability for above average conditions, near average conditions, and below average conditions for rainfall, temperature, soil moisture, and river flows. When a particular probability reaches or exceeds 60%, we conclude it is 'very likely'. This three-way probability means that a random choice would be correct only 33 per cent (or one-third) of the time. It would be like randomly throwing a dart at a board divided into three equal parts, or casting a dice with three numbers on it. Where probabilities are within 5% of one another, the term 'about equally' is used. All outlooks are for the three months as a whole. There will inevitably be relatively wet and dry days, and hot and cold days, within a season. The exact range in temperature and rainfall within each of the three categories varies with location and season. However, as a guide, the 'near average' or middle category for the temperature predictions includes deviations up to ±0.5°C for the long-term mean, whereas for rainfall the 'near normal' category lies between 80 per cent and 120 per cent of the long-term mean. The seasonal climate outlooks are an output of Predicting climate variability and change, a scientific research programme supported through NIWA's Strategic Science Investment Fund. The forecast confidence meter for temperature and rainfall represents the expert judgement of NIWA's climate scientists. It aims to synthesize various forecast elements, such as global and local climate drivers, in order to clearly communicate forecaster confidence in how all the evidence has aligned for the seasonal outlook.
Scoop
5 days ago
- Climate
- Scoop
NIWA Releases Seasonal Climate Outlook - June To August 2025
Air temperatures are expected to be above average across all New Zealand regions for this winter season, according to NIWA's Seasonal Climate Outlook for June - August 2025. While cold snaps and frost will occur, they are expected to be less frequent than usual, says NIWA Principal Scientist Chris Brandolino. Rainfall totals during the three months ahead are expected to be above normal for the north of the North Island and near normal for the east of the South Island. For all remaining regions of the country, rainfall is forecast to be near normal or above normal. Higher than normal atmospheric pressure is expected to the east of the country, leading to north-easterly flow anomalies that may shift to a more north-westerly direction towards the end of the three-month period. Low pressure systems forming north of the country are still expected to affect New Zealand and may lead to heightened risks for heavy rainfall events. Outlook Summary Neutral El Niño – Southern Oscillation (ENSO) conditions remain present in the tropical Pacific. Residual signals indicative of weak La Niña conditions persist, and occasional La Niña-like atmospheric patterns may still emerge over the next three months International guidance indicates about a 70% chance for the tropical Pacific to remain in an ENSO-neutral state over the outlook period. For New Zealand, higher than normal atmospheric pressure is expected to the east of the country, leading to north-easterly flow anomalies that may shift to a more north-westerly direction towards the end of the three-month period. Low pressure systems forming north of the country are still expected to affect New Zealand and may lead to heightened risks for heavy rainfall events. Seasonal air temperatures are expected to be above average across all New Zealand regions for this winter season. Thus, while cold snaps and frost will occur, they are expected to be less frequent than usual. Sea surface temperatures (SSTs) remain well above average around most of New Zealand, except in offshore areas east of the North Island. In May, coastal SST anomalies ranged from +0.39°C to +1.47°C. Large regions offshore are currently experiencing Marine Heatwave (MHW) conditions. Global climate models suggest that SSTs in the New Zealand region are likely to stay above average over the next three months, although the intensity of the anomalies may ease. Monitor the SST update for updates. June – August rainfall totals are expected to be above normal for the north of the North Island and near normal for the east of the South Island. For all remaining regions of the country, rainfall is forecast to be near normal or above normal. Sub-seasonal, or monthly, projections of rainfall and dryness are updated daily through the NIWA35 forecast. During June – August 2025, near normal soil moisture levels and river flows are expected for all regions of the North Island, while near normal or above normal soil moisture levels and river flows are forecast for the South Island. Regional predictions for June – August 2025 The tables below show the probabilities (or percent chances) for each of three categories: above average, near average, and below average. In the absence of any forecast guidance there would be an equal likelihood (33% chance) of the outcome for any of the three categories. Forecast information from local and global guidance models is used to indicate the deviation from equal chance that is expected for the coming three-month period. All outlooks are for the three months averaged as a whole. During these three months, there will inevitably be relatively wet and dry periods, as well as hot and cold periods. The exact range in temperature and rainfall within each of the three categories varies with location and season. However, as a guide, the 'near average' or middle category for the temperature predictions includes deviations up to ±0.5°C relative to the long-term mean, whereas for rainfall the 'near normal' category lies between 80 percent and 120 percent of the long-term (1991-2020) mean. Northland, Auckland, Waikato, Bay of Plenty Temperatures are very likely to be above average (65% chance). Rainfall totals are most likely to be above normal (45% chance) for June – August 2025 as a whole, with occasional heavy rain events expected. Soil moisture levels and river flows are most likely (45-50% chance) to be near normal Central North Island, Taranaki, Whanganui, Manawatu, Wellington Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are about equally likely to be above normal (40% chance) or near normal (35% chance). Soil moisture levels and river flows are most likely (40-45% chance) to be near normal. Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are most likely to be above average (45% chance). Rainfall totals are about equally likely to be near normal (40% chance) or above normal (35% chance). Soil moisture levels and river flows are most likely (45% chance) to be near normal. Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are equally likely to be above normal (40% chance) or near normal (35% chance). Soil moisture levels and river flows are equally likely to be near normal (40% chance) or above normal (40% chance). West Coast, Southern Alps and foothills, inland Otago, Southland Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are about equally likely to be near normal (40% chance) or above normal (35% chance). Soil moisture levels and river flows are about equally likely to be near normal (40% chance) or above normal (35% chance). Coastal Canterbury and the nearby plains, east Otago Probabilities are assigned in three categories: above average, near average, and below average. Temperatures are very likely to be above average (60% chance). Rainfall totals are most likely to be in the near normal range (40% chance). Soil moisture levels and river flows are about equally likely to be near normal (40-45% chance) or above normal (35-40% chance). The full probability breakdown is: Graphical representation of the regional probabilities Background Sea surface temperatures (SSTs) anomalies in the central equatorial Pacific (Niño 3.4 Index) in May (values estimated using data to 26 May) are in the ENSO-Neutral range (-0.08C). SSTs currently are slightly below average in parts of the central Pacific, and cooler than average surface waters have re-emerged along the Equator east of about 120oW. The warmer than average ocean waters previously observed off the South American coast have dissipated. The relative Niño 3.4 Index (RONI*) for the past 30 days (to 26 May) was -0.47C, placing it on the La Niña side of neutral, indicating that ocean temperatures in the central and eastern Pacific remain cooler than the tropical average. As of 26 May 2025, the preliminary Southern Oscillation Index (SOI) value for May is +0.68, indicating conditions on the La Niña side of neutral. Atmospheric indicators – such as enhanced trade winds (positive zonal wind anomalies) and stronger-than-normal convective activity over the Maritime Continent – continue to reflect lingering influences from the previous La Niña event. In May 2025, upper-ocean heat content (temperature anomalies in the upper 300 metres of the ocean) remained above average across the western tropical Pacific, particularly west of approximately 170°W. Anomalies exceeding +2°C persisted south of the Equator, from the Maritime Continent to the International Dateline, near the latitude of the Solomon Islands. East of the Dateline, while isolated areas north and south of the Equator exhibited negative anomalies, heat content along the Equator itself was generally near average. This distribution is consistent with the tropical Pacific Ocean having transitioned away from La Niña conditions. In the subsurface equatorial Pacific, ocean temperatures remained significantly above average (anomalies > +3°C) between approximately 100- and 200-metres depth west of 170°W. Over the past week, these warm anomalies have expanded eastward and risen in the water column, with above-average temperatures now observed below roughly 50 metres depth west of about 130°W. In contrast, the central and eastern Pacific show limited cooler anomalies, with only a single isolated pocket of below-average temperatures near 50 metres depth off the South American coast. Taken together, these indicators suggest that the tropical Pacific ocean has largely transitioned away from La Niña conditions observed earlier this year. Notably, the previously prominent east–west gradient in heat content and subsurface temperature anomalies has diminished. Based on the dynamical and statistical models monitored by NIWA, ENSO-Neutral conditions remain the most likely outcome (73% chance) over the next three-month period (June – August 2025). However, intermittent weak La Niña-like atmospheric patterns may still occur over the winter season. For the remainder of the calendar year, ENSO-Neutral conditions are expected to persist. The guidance available however suggests the possibility for La Niña conditions to return by summer 2025 – 2026. The Southern Annular Mode (SAM) was mostly positive during the month of May (85% of days positive) and the monthly average anomaly was +0.5 std. A positive SAM index is typically associated with higher pressure than normal over New Zealand. Over the next two weeks, the SAM is forecast to become temporarily negative and then return to slightly positive values. The Indian Ocean Dipole (IOD) is currently in the neutral range, with the average anomaly for the month of May* 2025 being +0.36oC. The guidance from the Australian Bureau of Meteorology is for the IOD to remain in the neutral range until at least July after which it is forecast to become negative. During May 2025, intra-seasonal convective activity associated with the Madden-Julian-Oscillation (MJO) was generally weak, despite a temporary increase in MJO amplitude over the Maritime Continent mid-May. The MJO is likely to remain weak or indiscernible in the coming two-week period. Sea surface temperatures (SSTs) remain significantly higher than average around much of New Zealand. The exception is off the east coast of the North Island, where SSTs are currently near average. Marine Heatwave (MHW) conditions – defined as five or more consecutive days with SSTs above the 90th percentile – are ongoing along the west and southeast coasts of the South Island, as well as the west and northeast coasts of the North Island. SST forecasts for the June – August 2025 period suggest a slight weakening of these anomalies. However, above-average ocean temperatures are expected to persist around New Zealand through the winter season. *The Relative Oceanic Niño 3.4 Index (RONI) is a modern way of measuring oceanic El Niño and La Niña that is complementary to oceanic traditional indices. While traditional oceanic indices like the Niño 3.4 Index monitor SSTs in one region, the RONI compares the average SST in the central equatorial Pacific with the average SST across the global tropics. Since tropical rainfall patterns respond to changes in ocean temperatures, this new relative index can help forecasters better determine if the equatorial Pacific is warmer or cooler than the rest of the global tropics, which has become more challenging to discern as seas warm because of climate change. Forecast Confidence Notes: NIWA's outlooks indicate the likelihood of climate conditions being at, above, or below average for the season as a whole, relative to the 1991-2020 average. They are not 'weather forecasts' as it is not possible to forecast precise weather conditions three months in advance. The outlooks are the result of the expert judgment of NIWA's scientists and forecasters. They take into account observations of atmospheric and ocean conditions and output from global and local climate models. The presence of El Niño or La Niña conditions and the sea surface temperatures around New Zealand can be useful indicators of likely overall climate conditions for a season. The outlooks state the probability for above average conditions, near average conditions, and below average conditions for rainfall, temperature, soil moisture, and river flows. When a particular probability reaches or exceeds 60%, we conclude it is 'very likely'. This three-way probability means that a random choice would be correct only 33 per cent (or one-third) of the time. It would be like randomly throwing a dart at a board divided into three equal parts, or casting a dice with three numbers on it. Where probabilities are within 5% of one another, the term 'about equally' is used. All outlooks are for the three months as a whole. There will inevitably be relatively wet and dry days, and hot and cold days, within a season. The exact range in temperature and rainfall within each of the three categories varies with location and season. However, as a guide, the 'near average' or middle category for the temperature predictions includes deviations up to ±0.5°C for the long-term mean, whereas for rainfall the 'near normal' category lies between 80 per cent and 120 per cent of the long-term mean. The seasonal climate outlooks are an output of Predicting climate variability and change, a scientific research programme supported through NIWA's Strategic Science Investment Fund. The forecast confidence meter for temperature and rainfall represents the expert judgement of NIWA's climate scientists. It aims to synthesize various forecast elements, such as global and local climate drivers, in order to clearly communicate forecaster confidence in how all the evidence has aligned for the seasonal outlook. See all of NIWA's media releases at:
Time of India
27-05-2025
- Climate
- Time of India
IMD predicts above-normal monsoon in Punjab, Haryana
Bathinda: The India Meteorological Department (IMD) on Tuesday released its updated long-range forecast for the 2025 monsoon (June–Sept), predicting significant rainfall surpluses in northern states. Tired of too many ads? go ad free now Punjab is forecast to receive over 115% of its seasonal average of 440 mm, while Haryana and Chandigarh are expected to see more than 114% of their normal 431 mm. Himachal Pradesh is projected to receive over 109% of its long period average of 734 mm. Both Punjab and Haryana recorded unusually high rainfall during the first 26 days of May. Rainfall in the monsoon core zone — which includes most rainfed agricultural regions — is also expected to be above normal (>106% of LPA), offering relief for farmers ahead of the critical sowing season. The IMD also anticipates above-normal rainfall for June, with forecasts suggesting levels over 108% of the LPA for the month. The forecast follows IMD's initial April 15 outlook, which projected a normal monsoon for the year. Currently, neutral El Niño–Southern Oscillation (ENSO) conditions prevail over the equatorial Pacific, and these are expected to persist throughout the monsoon season.
Indian Express
24-05-2025
- Climate
- Indian Express
Monsoon arrives early in Kerala, earliest onset since 2009: IMD
The southwest monsoon has made an early entrance into the Indian subcontinent this year, arriving over Kerala on Saturday — eight days ahead of its typical June 1 onset, the India Meteorological Department (IMD) said. This marks the earliest onset since 2009, when the monsoon reached the state on May 23. Over the past week, Kerala has witnessed a noticeable uptick in rainfall. The IMD declares the monsoon's arrival over Kerala based on three primary indicators: rainfall of at least 2.5 mm recorded at a minimum of 14 meteorological stations for two consecutive days, deep westerly winds extending up to 600 hectopascals, and a decline in Outgoing Longwave Radiation values below 200 watts per square meter. This early onset signals the beginning of the crucial four-month-long rainy season, vital to agriculture, water resources, and economic stability across the country. The Met department has issued warnings of extremely heavy rainfall — exceeding 205 mm in 24 hours — through Monday in Kerala and Mahe, with similar weather conditions forecast for coastal Karnataka. Adding to the turbulent weather, a well-marked low-pressure area off the Konkan-Goa coast intensified into a depression on Saturday and was expected to make landfall near Raigad in Maharashtra by evening. Squally winds and strong monsoonal currents were already prevailing across the Arabian Sea. This year, the IMD has forecast rainfall to be 'above normal,' estimating the total to be at 105 per cent of the Long Period Average (LPA) of 880 mm. Two major oceanic influences —the El Niño–Southern Oscillation and the Indian Ocean Dipole — are currently in a neutral phase, a condition expected to support monsoonal activity. The monsoon is projected to advance into the remaining parts of south peninsular and northeast India, along with additional areas of east and central India, between May 29 and June 4.
American Press
23-05-2025
- Climate
- American Press
NOAA's 2025 hurricane forecast warns of a busy season
(Metro Creative Services) U.S. forecasters are expecting an above-normal 2025 Atlantic hurricane season, with 13 to 19 named storms, and 6 to 10 of those becoming hurricanes. Every year, the National Oceanic and Atmospheric Administration and other forecasters release preseason outlooks for the Atlantic's hurricane season, which runs June 1 through Nov. 30. But, how do they know what's likely to happen months in the future? I'm an atmospheric scientist who studies extreme weather. Let's take a look at what Atlantic hurricane forecasts are based on and why those forecasts can shift during the season. What goes into a seasonal forecast Think of the preseason hurricane forecast as the 30,000-foot view: It can't predict if or when a storm will hit a particular location, but it can offer insight into how many storms are likely to form throughout the entire Atlantic, and how active the season overall might be. These outlooks rely heavily on two large-scale climate factors. The first is the sea surface temperature in areas where tropical cyclones tend to form and grow. Hurricanes draw their energy from warm ocean water. So when the Atlantic is unusually warm, as it has been in recent years, it provides more fuel for storms to form and intensify. The second key ingredient that meteorologists have their eye on is the El Niño–Southern Oscillation, which forecasters refer to as ENSO. ENSO is a climate cycle that shifts every few years between three main phases: El Niño, La Niña, and a neutral space that lives somewhere in between. During El Niño, winds over the Atlantic high up in the troposphere – roughly 25,000 to 40,000 feet – strengthen and can disrupt storms and hurricanes. La Niña, on the other hand, tends to reduce these winds, making it easier for storms to form and grow. When you look over the historical hurricane record, La Niña years have tended to be busier than their El Niño counterparts, as we saw from 2020 through 2023. We're in the neutral phase as the 2025 hurricane season begins, and probably will be for at least a few more months. That means upper-level winds aren't particularly hostile to hurricanes, but they're not exactly rolling out the red carpet either. At the same time, sea surface temperatures are running warmer than the 30-year average, but not quite at the record-breaking levels seen in some recent seasons. Taken together, these conditions point to a moderately above-average hurricane season. It's important to emphasize that these factors merely load the dice, tilting the odds toward more or fewer storms, but not guaranteeing an outcome. A host of other variables influence whether a storm actually forms, how strong it becomes, and whether it ever threatens land. The smaller influences forecasters can't see yet Once hurricane season is underway, forecasters start paying close attention to shorter-term influences. These subseasonal factors evolve quickly enough that they don't shape the entire season. However, they can noticeably raise or lower the chances for storms developing in the coming two to four weeks. One factor is dust lofted from the Sahara Desert by strong winds and carried from east to west across the Atlantic. These dust plumes tend to suppress hurricanes by drying out the atmosphere and reducing sunlight that reaches the ocean surface. Dust outbreaks are next-to-impossible to predict months in advance, but satellite observations of growing plumes can give forecasters a heads-up a couple weeks before the dust reaches the primary hurricane development region off the coast of Africa. Another key ingredient that doesn't go into seasonal forecasts but becomes important during the season are African easterly waves. These 'waves' are clusters of thunderstorms that roll off the West African coast, tracking from east to west across the ocean. Most major storms in the Atlantic basin, especially in the peak months of August and September, can trace their origins back to one of these waves. Forecasters monitor strong waves as they begin their westward journey across the Atlantic, knowing they can provide some insight about potential risks to U.S. interests one to two weeks in advance. Also in this subseasonal mix is the Madden–Julian Oscillation. The MJO is a wave-like pulse of atmospheric activity that moves slowly around the tropics every 30 to 60 days. When the MJO is active over the Atlantic, it enhances the formation of thunderstorms associated with hurricanes. In its suppressed phase, storm activity tends to die down. The MJO doesn't guarantee storms – or a lack of them – but it turns up or down the odds. Its phase and position can be tracked two or three weeks in advance. Lastly, forecasters will talk about the Loop Current, a deep river of warm water that flows from the Caribbean into the Gulf of Mexico. When storms pass over the Loop Current or its warm eddies, they can rapidly intensify because they are drawing energy from not just the warm surface water but from warm water that's tens of meters deep. The Loop Current has helped power several historic Gulf storms, including Hurricanes Katrina in 2005 and Ida in 2021. But the Loop Current is always shifting. Its strength and location in early summer may look very different by late August or September. Combined, these subseasonal signals help forecasters fine-tune their outlooks as the season unfolds. Where hurricanes form shifts over the months Where storms are most likely to form and make landfall also changes as the pages of the calendar turn. In early summer, the Gulf of Mexico warms up faster than the open Atlantic, making it a notable hotspot for early-season tropical storm development, especially in June and July. The Texas coast, Louisiana, and the Florida Panhandle often face a higher early-season risk than locations along the Eastern seaboard. By August and September, the season reaches its peak. This is when those waves moving off the coast of Africa become a primary source of storm activity. These long-track storms are sometimes called 'Cape Verde hurricanes' because they originate near the Cape Verde Islands off the African coast. While many stay over open water, others can gather steam and track toward the Caribbean, Florida or the Carolinas. Later in the hurricane season, storms are more likely to form in the western Atlantic or Caribbean, where waters are still warm and upper-level winds remain favorable. These late-season systems have a higher probability of following atypical paths, as Sandy did in 2012 when it struck the New York City region and Milton did in 2024 before making landfall in Florida. At the end of the day, the safest way to think about hurricane season is this: If you live along the coast, don't let your guard down. Areas susceptible to hurricanes are never totally immune from hurricanes, and it only takes one to make it a dangerous – and unforgettable – season.
