The July 2026 Wildfires in Canada and Their Transboundary Smoke Problem

Abstract

This Incident Brief examines the rapid escalation of Canada’s 2026 wildfire season and its transboundary smoke impacts. After a slow start, wildfire activity surged following the late-June North American Heat Dome. By 21 July, 3,915 fires had burned nearly 3.04 million hectares, with Ontario experiencing particularly severe conditions driven by high temperatures and dry weather. Smoke spread across Canada and the United States, affecting major cities including Toronto and New York. During 13–18 July, more than 769 million person-days of exposure to moderate or worse air quality were estimated, while nearly 106 million person-days were exposed to unhealthy, very unhealthy, or hazardous conditions between 15 and 17 July. The Brief highlights the disproportionate impacts on remote and Indigenous communities and calls for stronger wildfire prevention and response, evacuation preparedness, resilient infrastructure, public-health protection, and international cooperation as climate change increases wildfire and smoke risks.