Intense blazes burning in the United States and Canada are creating their own thunderstorms, which can spark more fires.

The monstrous fires that are now charring vast areas of western North America aren’t just colossal and fast-moving, they have also created their own thunderstorms — an example of exotic fire behaviour that scientists say is becoming more common as the climate changes.

Both the Park Fire, which has burnt more than 160,000 hectares in northern California, and the Jasper Fire, which has destroyed around one-third of the resort town of Jasper in Canada, have spawned ‘pyrocumulonimbus’ clouds, towering formations that can spit lightning, potentially starting more fires.

Reports of such clouds were relatively uncommon in years gone by.