MISSOULA — A weak system will bring scattered rain showers and thunderstorms to areas along the divide and northwest Montana Thursday afternoon. These will primarily be found from the Flathead Valley and east. All other locations will see mostly sunny skies with highs in the 80s.
Temperatures will remain in the 80s Friday with mostly to partly sunny skies. Friday will be a transitory day as the region begins to feel the start of the impending heat as it builds in from the west.
From Saturday onward, a Pacific high pressure system will strengthen and migrate east over the Northern Rockies. A prolonged period of excessive heat is expected from north-central Idaho into western Montana valleys, with the hottest temps likely to occur along the MT-200 and MT-2 valley corridors from the Idaho border to just west of the Flathead Valley. These locations (Troy, Libby, Trout Creek) could see temperatures range from 105-110 degrees starting Monday afternoon and lasting through Thursday evening.
Western Montana is no stranger to 100 degree heat as we usually have a few days in the 100s each year. However, heat like this in June and the longevity of this heat wave is what's so uncommon. Record breaking heat will be possible for 5 consecutive days starting next week (Monday - Friday). Also, since records started being kept, Missoula has reached 100 degrees only one other time in June, that was June 27, 2015. Missoula could reach the 100 degree mark for 5 straight days next week June 28 - July 2.