Smoke plumes from forest fires are interspersed among Canada’s numerous lakes. The fires, ignited mainly by lightning strikes, have increased in number over the last decade. Credit: NASA

The 2018 fire season is closing with conditions suitable for mid-autumn in western Canada and summer in the east. Therefore a ridge that has lingered over the central Pacific Ocean. And for the past two weeks has arched north and east. Therefore allowing a cold Arctic air mass to descend slowly over western Canada. This is sending an upper trough that has lingered along the west coast further south to lie from northern California to Baffin Island. This pattern is bringing rain, snow, and temperatures 10-15 degrees below normal for much of British Columbia, Alberta, and Saskatchewan. From a fire weather perspective, the cool temperatures and additional moisture will continue to reduce existing fire activity in western Canada. The upper flow swings quickly to the northeast over the eastern Prairies, leaving most of Manitoba and regions eastward in warm air. A few showers or thundershowers will continue to traipse across regions between Manitoba and northern Quebec.