Abstract

The 2023 wildfire season in Canada was unprecedented in its scale and intensity. Spanning from late April to early November and extending across much of the forested regions of Canada, the season resulted in a record-breaking total area burned of approximately 15 million hectares, over seven times the historic national annual average. The impacts were profound with more than 200 communities evacuated (approximately 232,000 people), periods of dense smoke that caused significant public health concerns, and unprecedented demands on fire-fighting resources. The exceptional area burned can be attributed to several environmental factors that converged early in the season to enable extreme fire danger over much of the country. These factors included early snowmelt, interannual drought conditions in western Canada, and the rapid transition to drought in eastern Canada. Furthermore, the mean May-October temperature over Canada in 2023 was a staggering 2.2°C warmer than normal (1991-2020), enabling sustained extreme fire weather conditions throughout the fire season. These conditions led to a larger than normal proportion of very large fires (> 50,000 hectares), many having burned for months from the spring into the fall. Fires that started in May or June accounted for over two-thirds of the total area burned. Overall, the 2023 wildfire season in Canada was characterized by its exceptional scale and major societal impacts, setting new records and highlighting the increasing challenges posed by wildfires in the country.