Glacier's weather is highly variable and can be extreme. Warm days and cool nights are the norm in summer. Even when it's in the 80s and 90s in the daytime it can cool down into the 40s at night. Hikers setting out on a warm summer day, should still bring along raingear and lots of extra clothing. Dressing in layers is key to a comfortable visit all year long.
For information on air quality in the park and surrounding region, please visit the Montana Department of Environmental Quality website.
Temperature & Precipitation Averages
Data in charts collected for West Glacier, Montana, which sits at around 3,200 ft in elevation (~975 m). The east side of the park is higher in elevation, therefore often cooler. It is frequently windy on the east side.
It is generally 10 to 15 degrees cooler at higher elevations, like Logan Pass. Overnight lows throughout the park can drop to freezing, and snow can fall anytime.
Glacier's geography, straddling the Continental Divide, sets the stage for clashes of two very different climates. Warm, wet Pacific air moves in from the west, and cold dry Arctic air from the northeast. They meet at the Divide. The western valleys generally receive the most rainfall, but daytime temperatures can exceed 90 degrees F. Strong winds and sunny days often predominate on the east side of the park.
The east side of Glacier is in a rain shadow and gets less overall precipitation than the west. The dryness of the east side is also due to high winds. Downslope winds are often 50 mph or more, sometimes reaching 100 mph. Warm chinook ("snow-eater") winter winds regularly create a temporary spring, raising temperatures over 30 degrees in just minutes. If the cold Arctic air pools deep enough on the east side, spills over the top, and collides with Pacific moisture, raging blizzards can result. One dumped 44 inches (1.1 m) of snow in a day.
Scientists stationed at Glacier are doing landmark research on the effects of global climate change in this mountain ecosystem. While precipitation changes are more difficult to predict than temperature, scientists expect to see more precipitation fall as rain (rather than snow) with a warming climate. This means snowpacks may not be as deep in the future.
Last updated: May 1, 2020