Summer weather will hold on one more days before we end the week with an autumn like cool air mass.
A few showers and thunderstorms are possible Tuesday evening across southwest Montana, around Butte and Bozeman, and northwest Montana, around Kalispell. Otherwise, partly cloudy overnight with lows in the upper 40s in Butte to the 50s in Missoula, Bozeman and Kalispell.
A Canadian cold front will sink south into northern Montana by late Tuesday. It will stall across the Kalispell area into central Montana. Cooler air will begin invading far northwest Montana, especially around Glacier Park. More showers and storms are possible there and again in southwest Montana around Bozeman and Butte with just a slight chance around Missoula. Highs in the upper 70s in Kalispell and Butte to the lower 80s in Missoula and Bozeman.
The front will gradually move through the rest of the area Thursday and Friday, ushering much cooler air into the region. Highs will drop to the upper 60s in Kalispell and Butte to the 70s in Bozeman and Missoula on Thursday, with further cooling to the 60s to around 70 Friday and the 50s in Butte to the 60s elsewhere on Saturday. During this entire period, there will be occasional showers. Otherwise, mostly cloudy. Lows by Sunday dropping to the 30s to lower 40s!
Another chance of showers early next week with the cool weather continuing.