A new global study shows a sharp rise in the number of days with weather conditions that fuel extreme wildfires. Over the past 45 years, the number of hot, dry, and windy days — ideal for fires to ignite and spread — has nearly tripled worldwide.
Researchers say human-caused climate change drives most of that increase.
The study, published in Science Advances, found that more than 60% of the rise in “synchronous fire weather days” comes from greenhouse gases released by burning fossil fuels like coal, oil, and natural gas.
What Is Synchronous Fire Weather?
Scientists use the term synchronous fire weather to describe days when multiple regions experience dangerous fire conditions at the same time.
That overlap creates serious problems.
When fires break out across several areas at once, countries cannot easily share firefighting crews, aircraft, or equipment. Neighboring regions often battle their own blazes. Resources stretch thin. Response times slow down. Suppression becomes harder.
Fire scientist John Abatzoglou from the University of California, Merced, says these conditions increase the chances of large, difficult-to-control wildfires. When multiple regions burn at once, emergency systems begin to strain.
The Numbers Show a Dramatic Rise
From 1979 through the early 1990s, the world averaged about 22 synchronous fire weather days per year. By 2023 and 2024, that number climbed to more than 60 days per year.
The Americas show some of the largest increases.
In the continental United States, the average rose from 7.7 days per year in the 1980s to 38 days per year over the past decade.
Southern South America saw an even more dramatic jump. That region averaged 5.5 days per year in the 1980s. Over the past decade, the average reached 70.6 days annually, including 118 days in 2023 alone.
Only Southeast Asia saw a decline, likely because increased humidity reduced fire-prone conditions.
Climate Change Plays a Major Role
The researchers did not study actual fires. Instead, they analyzed weather patterns: heat, dryness, and wind. These conditions create the perfect environment for flames to spread.
Fire needs four ingredients: heat, oxygen, fuel like trees or brush, and an ignition source such as lightning or human activity. Extreme weather increases the likelihood that those ingredients come together.
To measure climate change’s role, researchers used computer simulations. They compared today’s climate to a modeled world without fossil fuel emissions. The results showed that greenhouse gases account for more than half of the increase in dangerous fire weather days.
Why This Matters
Extreme fire weather drives larger, more destructive wildfires. It also changes how fire seasons behave. Regions that once burned at different times now overlap. That overlap reduces the ability to move resources where they are needed most.
As the planet warms, more regions may face fire-prone conditions simultaneously. That reality increases the global wildfire risk and challenges emergency response systems worldwide.
The trend does not guarantee fires everywhere. But it raises the odds.
And as fire scientists warn, when those odds rise across multiple continents at once, systems begin to break.
