The Autumnal Equinox, or fall, will begin at 8:29 Monday evening.
A storm system over Wyoming will bring a few showers and isolated thundershowers to southwest Montana Monday evening. The best chance is south of the Butte and Bozeman areas. Otherwise, partly cloudy with lows in the 40s in Bozeman, Butte and Kalispell to the lower 50s in Missoula.
A weak wave of moisture will move through the region Tuesday. There is a chance of an isolated shower or sprinkle from Missoula north into the Kalispell area. Otherwise, partly sunny and warm with highs in the 70s to around 80.
Near record breaking highs are expected Wednesday with sunshine. Highs will soar into the 80s and even up to 90 in the Missoula area. More sunshine is expected Thursday with highs in the 80s.
A big change to cooler and wet weather is likely by Friday and the weekend. A cold front will move into the region Friday bringing a chance of showers and thunderstorms. Highs in the upper 60s around Kalispell to the 70s elsewhere. More showers are possible this weekend. Highs only in the upper 50s and 60s.
So, we will go from much above average temperatures through Thursday to cooler than normal by the weekend!