Canadian forests are more conducive to high-severity fires in recent decades.

Canada has experienced more-intense and longer fire seasons with more-frequent uncontrollable wildfires over the past decades. However, the effect of these changes remains unknown. This study identifies driving forces of burn severity and estimates its spatiotemporal variations in Canadian forests. Our results show that fuel aridity was the most influential driver of burn severity, summer months were more prone to severe burning, and the northern areas were most influenced by the changing climate. About 6% (0.54 to 14.64%) of the modeled areas show significant increases in the number of days conducive to high-severity burning during 1981 to 2020, most of which were found during 2001 to 2020 and in the spring and autumn. The extraordinary 2023 fire season demonstrated similar spatial patterns but more-widespread escalations in burn severity.