Canada is burning more than ever because rising temperatures, decades of fire suppression, and a vast boreal forest uniquely vulnerable to drought have collided. In 2023, fires scorched an estimated 18.4 million hectares, an area roughly the size of North Dakota and more than seven times the annual average of 2.5 million hectares. That season wasn’t a freak event. It was the clearest signal yet of trends that have been building for decades.
Canada Is Warming Twice as Fast
The single biggest driver is temperature. Canada’s average annual temperature rose by 1.7°C between 1948 and 2016, about double the global rate. In northern Canada, above 60 degrees latitude, warming has been even steeper: 2.3°C over the same period, roughly triple the global average. That extra heat does two things that matter for fire. It dries out vegetation faster, and it extends the window in which fires can ignite and spread.
Warmer air holds more moisture, which sounds like it should help. But when humidity doesn’t keep pace with rising temperatures, the atmosphere actually pulls water out of trees, shrubs, and forest litter more aggressively. Scientists measure this drying force as vapor pressure deficit, essentially how thirsty the air is. Higher vapor pressure deficit means woody fuels lose moisture faster, ignite more easily, and burn more intensely. This mechanism has been strongly linked to larger burned areas across North American forests.
Earlier Springs, Longer Fire Seasons
Snowpack acts as a natural fire break. As long as snow covers the ground and keeps soils wet, fires can’t take hold. But warmer springs mean snow melts earlier, and the landscape dries out sooner. In 2023, a significant moisture deficit was already spreading across the country by early April, weeks ahead of the typical fire season. That year, fires burned from mid-April all the way through late October.
This pattern is expected to intensify. Forecasted warming in spring and fall temperatures will push the fire season earlier and later, especially in regions where winter precipitation declines. A fire season that once ran roughly from June through August now regularly stretches across six or seven months, giving fires far more opportunity to start and grow.
Lightning Drives the Biggest Fires
About half of Canada’s wildfires are started by people and half by lightning. But the fires ignited by lightning account for roughly 90% of the total area burned. The reason is geography. Human-caused fires tend to start near roads, towns, and campsites, where firefighters can reach them quickly. Lightning strikes deep in remote boreal forest, often during dry thunderstorms that deliver no rain. Those fires can burn unchecked for days or weeks before crews even reach them, consuming enormous stretches of wilderness.
Climate change is increasing the frequency of lightning in some northern regions as warmer temperatures fuel more convective storms. More lightning in more remote forest, during longer dry spells, is a recipe for exactly the kind of massive fires Canada has been seeing.
A Century of Fire Suppression Built Up Fuel
Wildfires burned freely across most of Canada until the late 19th century. Then European-influenced forestry policies made suppression the default: put out every fire as fast as possible. That approach protected timber and communities in the short term, but it allowed dead wood, underbrush, and dense stands of trees to accumulate across millions of hectares. Forests that historically thinned themselves through periodic burns became packed with fuel.
Insect infestations have compounded the problem. Warming winters have allowed bark beetles and other forest pests to survive in areas that were once too cold, killing vast stands of trees and leaving behind dry, highly flammable wood. When fire does reach these areas, it burns hotter and faster than it would in a healthier forest.
The Boreal Forest Is Uniquely Vulnerable
Canada’s boreal forest stretches across roughly 270 million hectares, forming one of the largest intact forest ecosystems on Earth. Much of it sits on deep layers of peat, partially decomposed plant material that has accumulated over hundreds or thousands of years. Cold, wet conditions in the far north historically slowed the breakdown of organic matter, locking enormous amounts of carbon underground.
As the climate warms and droughts intensify, those peat soils dry out and become combustible. Fires can spread downward into thick layers of carbon-rich soil beneath the forest floor, smoldering for weeks, months, or even years. These slow, underground burns are sometimes called “zombie fires” because they can survive an entire winter beneath snow, then reignite the following spring. From space, these smoldering peat fires look small, but they release massive amounts of ancient carbon, creating a feedback loop: more fire releases more carbon, which drives more warming, which creates conditions for more fire.
Stalled Weather Patterns Lock In Heat
Individual fire seasons become catastrophic when the jet stream, the river of fast-moving air high in the atmosphere, stalls. Normally the jet stream pushes weather systems across the continent in a matter of days. But it can develop large, persistent bends that park a dome of high pressure over a region for weeks. These blocking patterns trap hot, dry air in place, creating the prolonged heatwaves and droughts that turn large landscapes into tinderboxes.
Research has found that persistent ridging in the upper atmosphere is a common feature of extreme fire events across North America. In western Canada, these ridge patterns tend to last longer than in the east, which partly explains why provinces like British Columbia and Alberta see some of the most destructive fire seasons. When a blocking pattern settles over a region already primed by early snowmelt and dry fuels, the result can be weeks of uninterrupted fire weather with no relief in sight.
Growing Human Cost
Between 1980 and 2021, Canada recorded 1,393 wildfire evacuation events displacing a total of 576,747 people. The trend is climbing steadily, with roughly 392 additional evacuees per year and about one additional evacuation event per year over that period. The worst single year was 2016, when over 101,000 people were forced from their homes, largely due to the Fort McMurray fire in Alberta.
Evacuations are also lasting longer. From 1980 to 2007, the average evacuation lasted 5.6 days. From 2008 to 2021, that nearly doubled to 10.9 days. The total economic cost of wildfire evacuations over the four-decade study period was estimated at 3.7 billion Canadian dollars, rising to 4.6 billion when lost productivity was included. Those figures don’t account for homes and infrastructure destroyed.
The fires of 2023 dwarfed anything in the historical record, blanketing large parts of eastern North America in smoke and forcing evacuations in nearly every province. What made that season so extreme wasn’t any single new factor. It was all of the existing factors, warming temperatures, early snowmelt, dry fuels, lightning ignition, and a stalled jet stream, arriving at once and reinforcing each other across an unprecedented geographic range.