Synchronized wildfire weather is straining global firefighting networks

For decades, countries like the United States, Australia, Canada, and South Africa have shared firefighting crews and aircraft when one nation faces an overwhelming season and others do not. That arrangement depended on a simple assumption: not everyone would need help at the same time.

That assumption is increasingly wrong. A new global analysis published in Science Advances on February 18, 2026, shows that extreme fire weather conditions are hitting multiple regions simultaneously far more often than they did 45 years ago, compressing the windows when international resource-sharing is possible and potentially overwhelming the cooperative systems built to manage the world's worst blazes.

Mapping a global phenomenon for the first time

Scientists at the University of East Anglia (UEA) and the University of California, Merced, analysed daily Fire Weather Index values worldwide from 1979 through 2024, tracking when extreme fire-risk conditions aligned across large regions or multiple continents on the same day. Previous research had examined synchronous fire weather in specific places such as the western United States or Europe. This is the first study to measure it globally and distinguish between two types: synchronicity within a region, where many locations in the same area face peak danger simultaneously, and synchronicity between regions, where two or more distant regions face it on the same day.

The results are striking. In many parts of the world, the number of days when extreme fire weather strikes multiple areas simultaneously has more than doubled since 1979. North America, Europe, Boreal Asia, the Middle East, and South America face the highest levels of inter-regional synchronicity, with at least one other region sharing extreme conditions for more than 30 days per year on average.

Portugal and Spain are among the hardest-hit examples

The geographic hotspots for increased strain on firefighting cooperation networks are identifiable. In Portugal and Spain, the count of same-day extreme fire weather days has risen by more than 12 days per year since 1979. Between the United States and South Africa - two nations with established bilateral firefighting agreements - the average is now four same-day extreme fire weather events per year, a figure increasing at 1.2 days per decade.

In lower- to mid-latitude regions including South America, Central and East Asia, Africa, and the mainland United States, the annual count of these days during 2001 to 2024 was three to seven times higher than during 1979 to 2000.

When synchronous fire weather peaks, air quality degrades over large areas simultaneously, not just near local fires. In Europe, during the worst 25 percent of years for synchronous fire weather, population exposure to fire-sourced air pollution runs almost 200 percent higher than in other years.

Climate change is the primary driver - but not the only one

The research team, which also included scientists from the University of Washington and Boise State University, used statistical methods to separate the contributions of human-caused climate change from natural variability. Their estimate: more than half of the observed increase in synchronous extreme fire weather is attributable to anthropogenic climate change. Natural climate patterns can still matter locally - in Equatorial Asia, El Nino years produce significant spikes in simultaneous fire weather days - but the long-term upward trend is predominantly human-driven.

"The rise in extreme fire risk days that happen at the same time puts unneeded pressure on firefighting agencies, with simultaneous fire weather reducing the number of days when resources can be shared across international borders or state divisions within countries," said Dr. Matthew Jones of the Tyndall Centre for Climate Change Research at UEA. "This ultimately makes wildfires more difficult to deal with at the times when they are most threatening."

When everyone needs help at once

International firefighting cooperation has a strong track record. During the 2023 Canadian fire season, when hundreds of blazes destroyed homes across vast stretches of land, crews from South Africa and other countries arrived to help. That model works when fire seasons are staggered. It faces structural pressure when peak danger aligns globally.

Dr. Cong Yin, of UC Merced and the Chinese Academy of Sciences, explained the core problem: "When extreme fire weather happens in many places at once, it increases the likelihood of widespread fire outbreaks and strains firefighting capacity, because crews, aircraft, and equipment cannot be easily shared when everyone needs help at the same time."

The study's scope covers 45 years of global weather data, giving it a long baseline. But it cannot directly measure whether specific fires were worse because of synchronicity, or whether cooperation failures have already occurred as a result. The authors note their analysis identifies risk windows, not confirmed coordination breakdowns. Future work connecting synchronous fire weather to specific instances of depleted international resource sharing would strengthen the practical implications.

Jones and Yin call for "more robust and adaptive" global fire management strategies, including early warning systems capable of flagging emerging multi-region risk windows, enhanced coordination protocols, and clear communication channels between national agencies. The goal is to preserve the capacity for international cooperation precisely when simultaneous danger makes it hardest.