Why are wildfires becoming more frequent across North America? Causes explained
The seasonal outlook had previously flagged above-normal risk for Texas, Florida, Georgia, the Carolinas and the broader southeastern region of the United States, largely linked to dry and warm patterns driven by La Nina.
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Canada’s season was equally eventful. By mid-July, more than 800 wildfires were burning across the country, with large clusters appearing in Ontario near the Minnesota border, according to the Canadian Interagency Wildfire Center (CIFFC).
While Ottawa’s own outlook points to above-average conditions for the remainder of the season, British Columbia, Alberta and the Northwest Territories face the highest risk.
How does climate change affect forest fires?
Scientists attribute this trend to a warming atmosphere rather than weather conditions in any given season. The National Oceanic and Atmospheric Administration (NOAA) says increased heat, longer droughts and a “thirtier” atmosphere are a major factor in the increased wildfire risk in the Western U.S. over the past two decades, as temperature, humidity and fuel moisture are closely linked to climate change.
A study published in 2016 in the Proceedings of the National Academy of Sciences by John Abatzoglou and A. Park Williams found that climate-induced drying roughly doubled the cumulative area of wildfire burned in the western U.S. between 1984 and 2015. A follow-up PNAS study in 2021 by UCLA researchers led by Yizhou Zhuang concluded that human-induced warming was responsible for the majority of the increase in wildfires. Risk of “fire weather” in the area.
NASA says the fire season in some parts of the U.S. is about a month longer than it was 35 years ago; This situation is also seen in Mexico, Brazil and East Africa. Global carbon emissions from wildfires increased by 60% between 2001 and 2023.
Heat waves, drought and dry forests explained
The mechanism is pretty direct: Heat draws moisture from the vegetation, and the dried vegetation becomes fuel. “The more you see [widespread heat]”The more evaporation there is, the more drought there is,” AccuWeather senior meteorologist Paul Pastelok told Reuters.
Rising temperatures are creating drier, drought-like conditions that make wildfires more destructive and harder to control, the report said.
California is a vivid example this year. According to CAL FIRE, spring 2026 was warmer and drier than normal across the state; Since October, the south has seen precipitation at about 70% of average, with Sierra snowpack dropping from 75-80% of normal on May 1 to just 20-30% by the end of the month.
Which regions face the highest risk of wildfire?
Western Canada and the Western United States remain the most exposed. British Columbia, Alberta and the Northwest Territories are marked for the highest wildfire risk in Canada this season. According to CAL FIRE data, the U.S. is expected to see above-normal major fire activity throughout July and August in both Northern and Southern California; Early season timber fires are already being recorded in high forests above 7,000 feet in the Sierra.
Washington state will face above-average risk for the entire state through August, following an early-season drought and a statewide drought emergency declared in April.
Outside of the West Coast fire belt, Texas, Florida, Georgia, the Carolinas and the broader southeastern region of the United States are also flagged for above-normal risk in NIFC’s national outlook this year.
How do forest fires affect air quality?
North America is experiencing this right now. Smoke from more than 800 active wildfires in Canada triggered air quality warnings in mid-July in at least 18 U.S. states, stretching from Minnesota to New Hampshire to Virginia. City officials noted that New York City’s Air Quality Index was above 200, rated “very unhealthy,” while Milwaukee recorded its worst air quality on record, with an AQI of 644, more than double the previous 1987 record.
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Health risk depends on particle size. According to the U.S. Centers for Disease Control and Prevention (CDC), wildfire smoke can trigger coughing, wheezing, shortness of breath, eye and throat irritation, and trigger asthma attacks, bronchitis, and COPD attacks.
The smallest particles, called PM2.5, can travel hundreds of kilometers from the fire and infiltrate the lungs and bloodstream, increasing the risk of heart attack, stroke and respiratory illness with repeated exposure.
Can forest fires be prevented?
Most, but not all, ignition is under human control. According to the U.S. National Park Service, 89 percent of wildfires are human-caused; Stray campfires, discarded cigarettes, burning debris, faulty equipment, downed power lines and arson are among the main triggers.
Land managers rely heavily on prescribed, controlled burns to reduce future risks. These low-intensity fires are set under light winds, high humidity and low temperatures to clear away dead leaves, dry grass and small branches before feeding a larger fire.
The U.S. Forest Service uses prescribed fire to reduce hazardous fuels and protect communities from more severe wildfires later in the season; He points out that decades of fire exclusion have left many ecosystems overcrowded and primed to burn hotter.
Property-level defenses are also important. Most homes are ignited not directly from flames but from wind-borne embers that can travel up to a mile ahead of the fire front; Therefore, in addition to defensible space, home-hardening measures such as fire-resistant roofing and fine-mesh vents are also emphasized.
