Hundreds of miles south, the communities facing new, mandatory evacuation orders on Friday night included Edson, a town of about 8,000 people that is less than 150 miles west of Edmonton, Alberta’s provincial capital.

In neighboring British Columbia, the same unseasonably warm weather has caused snowpack to melt rapidly, setting off flooding and mudslides. A number of flood warnings and other advisories were in effect across the province early Saturday.

In the United States, warm, dry and windy conditions in the Southwest and the Southern Plains were expected to create weather conducive to wildfires over the weekend, the National Weather Service warned in a forecast. More than three million people in that part of the country were under fire-related warnings or watches early Saturday morning.

Wildfires are increasing in size and intensity in the Western United States, and wildfire seasons are growing longer. Recent research has suggested that heat and dryness associated with global warming are major reasons for the increase in bigger and stronger fires.

In Alberta, early spring tends to be the time of greatest risk for wildfires. That is partly because spring snow melt leaves a significant amount of dead grass and other potential fire fuel on the land.