24-05-2025
Rain still pours across Indonesia with ‘wet dry season' expected until June
JAKARTA: While Indonesia typically starts entering the dry season around April, heavy rainfall has continued in most parts of the country in the past few weeks, with the 'wet dry season' expected to last until early June.
Earlier this year, the Meteorology, Climatology and Geophysics Agency (BMKG) forecasted that Indonesia would see a normal dry season that would start in most areas in April and was expected to reach its peak between June and August.
A normal dry season occurs when there is not a dominant El Niño weather pattern.
El Niño tends to bring drier air to the archipelago, resulting in a prolonged dry season.
But in its latest reports, the weather agency forecasted that the dry season would start later in some areas. It will also be shorter in most regions.
In a forecast report issued on Thursday, BMKG recorded that 73 percent of the archipelago is still experiencing a wet season, which usually falls from October to April.
Most regions see clear weather between morning and early afternoon, followed by thunderstorms that last until the evening.
'The weather dynamics in most parts of Indonesia show a transitional period between the rainy and dry season, which is locally known as pancaroba,' the agency wrote.
The wetter start of the dry season could be attributed to some atmospheric phenomena, such as Madden-Julian Oscillation (MJO), a moving pulse of wind, cloud and atmospheric pressure that brings extra water vapor to form clouds in the sky.
The MJO contributes to the formation of rain clouds and triggers more rain, particularly in the southern and central parts of the country, according to BMKG head Dwikorita Karnawati.
The Indonesian archipelago's location near the equator allows the country to be exposed to regular amounts of sunlight, leading to a greater chance of precipitation.
'In general, rain intensity is expected to start decreasing by the end of May until early June,' Dwikorita said.
Anomalous, yet normal
The shift between the rainy and dry season in Indonesia is mostly influenced by the monsoons, a seasonal prevailing wind that lasts for several months.
When the wind blows from Asia to Indonesia, it brings moist air from the South China Sea, triggering the rainy season in the country from October and March.
But when the other monsoon blows from April to November, the wind is dry as it passes through the desert areas in the northern part of Australia.
This monsoon results in decreased rainfall in Indonesia, triggering a dry season across the archipelago.
In May this year, Indonesia is experiencing stronger Asian monsoon winds compared to the average of the last two decades, said meteorologist Deni Septiadi from the State College of Meteorology, Climatology and Geophysics (STMKG).
The strong monsoon winds from Asia, he added, are disrupting the timing and strength of their counterpart that blows from Australia.
Deni said the phenomenon could be attributed to several factors: 'One of them could be the heavily concentrated rain clouds over Indonesia. At the same time, the Asian monsoon is still blowing strong.'
Despite the late start of the dry season, BMKG meteorology deputy Guswanto said that the condition is still considered normal as the country is in the pancaroba phase, which usually features high humidity and increasing sea temperatures that can fuel the formation of rain clouds.
'Now we're still in the pancaroba phase, which means that the wet dry season may be observable in several areas where rain still falls,' Guswanto said.
Pancaroba can occur twice a year for three months each during the transition from the dry to wet season and vice versa.
Based on the current timing, the dry season will fall in most parts of the country from June to August, followed by pancaroba in September and then a wet season from December, according to Guswanto.
Personnel of a joint search and rescue team break down a house buried in a landslide triggered by torrential rains in Trenggalek, East Java on Thursday, the third day of a search and rescue operation to locate six missing people. - Photo: Antara
Disaster warning
Guswanto said that a silver lining to the wetter start of the dry season is that the weather can help boost crop output.
Meanwhile, Dwikorita urged the public to stay alert about the possibility of heavy rain that can trigger disasters, even as rain intensity is expected to decrease.
Heavy rain in Jakarta on Wednesday inundated at least two neighborhood units (RT) and four major roads, causing heavy traffic that lasted until late at night.
High rain intensity also triggered a flood in South Barito regency in Central Kalimantan early Thursday morning, affecting nearly 7,000 people and inundating more than 1,300 houses and public buildings.
Torrential rain also triggered landslides in Trenggalek, East Java and Mimika, Central Papua, with dozens of people trapped and missing in both locations.
BMKG warned that thunderstorms and strong winds can still occur in several regions, such as across Java Island, North Sumatra, Central Kalimantan, Maluku and South Papua. - The Jakarta Post/ANN
