Why an intense fire season forecast in Canada is bad news for communities across the US

CNN

14-05-2025

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It could be another dangerously smoky summer for some in the United States as Canada prepares for a busy wildfire season with forecasts also signaling extreme heat is in store for both countries in the coming months.
But when it comes to wildfire threats this season, the call is also coming from inside the house for the US: Violent wildfires have already raged in multiple states this year, millions were under red flag warnings this week and an active summer is on the horizon.
In Canada, wildfires have scorched tens of millions of acres, displaced hundreds of thousands of people and killed multiple firefighters since the country's record-breaking 2023 fire season.
Some fires from the past two years also poured smoke into large population centers in Canada and the US, cratering air quality and ushering in orange-tinted, apocalyptic-looking skies.
Planet-heating fossil fuel pollution is tipping the odds that wildfire seasons like 2023 and 2024 – Canada's worst season on record and its second-worst season of the century, respectively – won't remain outliers for long.
Here's what we know about this year's Canadian wildfire forecast and how impacts could cross the border.
Western Canada is likely to be the epicenter for fires this season. The region is at a greater risk for destructive wildfires than provinces further east, like Ontario and Quebec, because it experiences drier and windier conditions.
Wildfires can happen at any time of the year, but May is typically the month where fire activity starts to pick up in Western Canada, according to Richard Carr, a wildfire research analyst and meteorologist with the Canadian Forest Service.
'Generally, we start to see a few small fires pop up in March and a few in April, but things don't usually get going until we get into May or beyond,' Carr explained, but noted fires have started to crop up earlier than normal in recent years.
'Before we get vegetation greening up completely, it's more susceptible to burning,' Carr said.
More than 300,000 acres of land in Canada have burned as of May 13, which is much less than the 4 million acres scorched by that point last year and around the 25-year average of 280,000 acres, according to data from the Canadian Interagency Forest Fire Centre.
Western Canada's fire season typically has a slight dip in severity in the late spring when plants have greened up, until intense summer heat arrives and dries out the ground and fuels again.
Above-average fire weather severity is forecast for almost all of Western Canada in June and July, but things could take a turn to the extreme in August, according to Natural Resources Canada. Well-above average fire weather severity is forecast for Western Canada with level 5-of-5 extreme severity projected in southern British Columbia, Alberta and Saskatchewan where millions of people live.
Despite the concerning forecasts, a repeat of the previous two wildfire seasons isn't guaranteed.
Widespread drought conditions were in place in early spring of 2023 and 2024 and only worsened through summer. While drought is affecting some areas this spring, it's much less widespread than years past, according to the latest Canadian Drought Monitor.
But the lack of an El Niño or La Niña – with so-called neutral conditions in effect instead – could also play a role. El Niño and La Niña are the warm and cool sides of the El Niño Southern Oscillation (ENSO), a climate pattern based on sea-surface temperatures in the tropical Pacific Ocean. They exert a known influence on weather patterns around the globe that can be forecast months in advance, but neutral conditions tend to have less consistent effects overall.
Despite this, neutral ENSO conditions have historically been troubling for Canada's wildfire season as they match up with some significant fire years in British Columbia, according to Carr.
Neutral ENSO years typically have weather that's warmer and drier than normal – exactly what's shown in this summer's forecasts from Environment and Climate Change Canada. A similar forecast is in effect for parts of the American West.
Large wildfires produce dangerous smoke that can reach communities hundreds of miles away.
The most extreme recent example of this happened in June 2023, when thick smoke from out-of-control, historic fires in Quebec choked the northeastern US. New York City briefly had the worst air quality in the entire world as smoke made the city's iconic skyline vanish.
Wildfire smoke contains very dangerous, tiny pollutants called PM2.5 that can travel deep into the lungs or enter the bloodstream when inhaled. The minuscule particles can lead to breathing problems like bronchitis and cause inflammation that aggravates diabetes, heart disease and other health conditions.
It's impossible to know exactly where smoke from potential wildfires this season will go, but there are a few common scenarios that could bring smoke into the US again. Because the most extreme fire risks are mainly confined to Canada's western provinces this season, cities in the northwestern US states are most likely to face international smoke troubles based purely on proximity. But different atmospheric setups can drag smoke much farther away.
Heat domes – large areas of high pressure that park over an area for days – prevent wet or windy weather from happening underneath them and instead force active weather to move along their northern periphery. They often set up over parts of the West and Plains in the summer.
Wildfire smoke could be directed over the northern US and into parts of the East if it were to flow out of Canada while a heat dome is stuck over the Plains. Smoke could also flow into the central US if a heat dome sets up over the Southwest.
Where and how quickly summer storm systems track through the US also play a role in transporting smoke. A slow-moving storm in the northern US could easily pull smoke south out of Canada – that's exactly what happened to the Northeast in June 2023.
Canadian fires won't pose the only smoke risk for the US as wildfire risks ramp up in the western states in the summer, too. Much of the US West will have above-normal wildfire potential by July and increase into August, according to National Interagency Fire Center forecasts.
The type of weather that fuels wildfires – dry air and strong winds – is coming together more frequently in parts of Canada and the US as the world continues to warm. And, the most extreme wildfires in North America are getting more intense.
The number of days each year with fire weather conditions in place is increasing for much of the US, but nowhere more so than the Rockies and areas west, a recent study from non-profit research group Climate Central found. Parts of Southern California, New Mexico, Texas, and Arizona now see 'around two more months of fire weather per year compared to a half century ago,' according to the study.
A small spark could ignite a raging inferno when weather conditions are primed for fire start and spread, and climate change is also loading the dice toward an insidious smoke threat.
Climate change caused approximately 15,000 more deaths in the US from wildfire particulate matter from 2006 to 2020 than would have otherwise occurred in a cooler world, a study published this month found.
More than 700,000 people could die from climate change-driven wildfire smoke over the next 30 years in the US and cost $244 billion per year by 2050, according to a study last year.
CNN's Jen Christensen contributed to this report.