Montana weather is notoriously unpredictable. It is a very large state with incredibly varied topography, so weather can be very different across the state on any given day. Given the relative lack of humidity, temperatures can fluctuate as much as 40 degrees on any given day. Regardless of the timing of your visit, it is recommended to pack some warm close as well as rain gear to ensure your comfort.
April and May
Spring can be a wonderful time in Montana. Snow blankets the mountains while the valleys become an intense, bright green. Good weather days will see sunny skies with temperatures in the 50s to 70s. We still see some snow this time of year, even in the valleys, although it tends to melt of fairly quickly. Stormy days typically see temperatures in the 30's to 50's, with rain or snow, depending on the elevation. It is very important that visitors to Montana this time of year bring dress for all 4 seasons.
June
June is the transition from spring to summer in Montana. Early June can be very springlike, with mild temperatures and some wet weather. By the middle of June, however, summer has really set in with temperatures in the 70's and 80's, broken only occasionally by a passing afternoon shower.
July and August
July and August are high summer in Montana, with many days of ideal weather. This time of year is typically very dry, with occasional afternoon thundershowers. Temperatures are typically in the mid-80's to low-90's, with very low humidity leading to nice, cool nights.
September
September is the transition between summer and fall in Montana. Mornings become cooler, but sunny afternoons will typically warm into at least the 60s. Low pressure systems do roll in during September, but these are almost always in the form of rain rather than snow.
October
October is fall in Montana. Expect temperatures in the 30's and 40's in the mornings, with highs typically in the 50's. Like September, October will see a mix of beautiful sunny days and low-pressure systems producing rain and snow. We always see some snow in October, so make sure to be prepared.
