As North America heads into the heart of wildfire season, both Canada and the United States face heightened risks not only from the fires themselves but also from the widespread and dangerous wildfire smoke that can travel hundreds of miles, impacting millions far from the flames.
Rising Risk Across Canada and the U.S.
Wildfire experts anticipate a particularly active summer, especially across Western Canada and the western United States. Above-average temperatures and dry conditions are forecast through July and August, increasing the likelihood of large, fast-moving fires.
Although Canada has seen a slower start compared to 2023 — its worst fire season on record — over 300,000 acres have already burned as of mid-May. Conditions are expected to worsen by late summer, with regions like British Columbia, Alberta, and Saskatchewan facing extreme fire weather severity ratings. Meanwhile, U.S. wildfire risk is expected to escalate across the West by July.
What makes this year especially concerning is the combination of widespread drought, warmer-than-average weather, and neutral ENSO (El Niño-Southern Oscillation) conditions. Unlike El Niño or La Niña, which influence weather patterns in predictable ways, neutral ENSO years tend to bring inconsistent but often dry and warm conditions — the kind that support severe wildfire seasons.
Why Wildfire Smoke Is a Growing Concern
As the frequency and intensity of wildfires increase, so does the risk from wildfire smoke — a less visible but more widespread public health threat. In 2023, smoke from Canadian wildfires plunged U.S. cities like New York and Chicago into hazardous air quality levels, temporarily giving them some of the worst air conditions in the world.
The smoke from wildfires contains tiny particles known as PM2.5 — microscopic pollutants that can penetrate deep into the lungs and even enter the bloodstream. Prolonged exposure has been linked to respiratory issues, heart disease, and aggravated chronic conditions like asthma and diabetes. Vulnerable populations, including the elderly and children, are especially at risk.
Forecast models suggest that if large-scale fires ignite in Western Canada again this year, cities in the Pacific Northwest and northern U.S. states will be most at risk for smoke exposure. However, shifting atmospheric patterns such as jet streams or high-pressure heat domes can move smoke much farther east or south.
How Heat Domes Influence Smoke Travel
A phenomenon known as a “heat dome” — where a large high-pressure system traps hot, dry air over a region — can worsen wildfire conditions and influence where smoke travels. When these systems settle over the central U.S., for instance, smoke from Canadian or northern U.S. fires may flow eastward, reaching major population centers like the Midwest or Northeast.
Storm systems also play a role. A slow-moving low-pressure system in the northern U.S. can pull smoke across the border and distribute it over broad areas. These dynamics make it nearly impossible to predict exact smoke impacts in advance, but meteorologists can often identify patterns a few days ahead.
A Long-Term Threat Linked to Climate Trends
Climate data shows a long-term increase in the number of days per year with “fire weather” — conditions primed for ignition and spread. Across much of the western U.S., the fire season is now two months longer than it was 50 years ago. Areas like Southern California, New Mexico, and Arizona are especially affected.
This pattern is expected to continue. Without significant reductions in global greenhouse gas emissions, both the frequency and intensity of wildfires — and associated smoke — are likely to grow. The implications for public health are staggering. Recent research estimates that tens of thousands of additional premature deaths in the U.S. over coming decades could be linked to wildfire smoke exposure alone.
Preparedness and Mitigation
Individuals can take proactive steps to reduce their exposure. These include using air purifiers indoors, sealing windows during smoke events, and checking local air quality indexes during peak wildfire months.
For vulnerable groups or those in high-risk areas, creating a clean air space inside the home or identifying community shelters with filtered air systems may become increasingly important during peak wildfire periods.
🌫️ June 2023: When Smoke Blanked Out the Skyline
In June 2023, smoke from massive wildfires in Quebec drifted over the U.S. Northeast, sending air quality plummeting. For several days, New York City experienced visibility reductions and hazardous PM2.5 levels, leading to canceled outdoor events and public health warnings. It was a stark reminder of how wildfires hundreds of miles away can affect urban centers unprepared for such events.
As the 2025 fire season unfolds, wildfire smoke remains a serious and unpredictable risk. While fire itself is often localized, smoke knows no borders — making international cooperation and public awareness critical tools in protecting health and safety during this high-risk period.