Weather

Visitors should be ready for all kinds of weather conditions.

NPS

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.

Forecasts

For a current weather forecast of the entire park, please check Todays Forecast, (or for a text version of the forecast). More detailed forecasts can be found at West Glacier and St. Mary.

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.

 

CLICK TO ENLARGE

NPS Graphic

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.

 

The Divide

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.

Precipitation
In the driest corners of the park, along the northeast and northwest edges, rainfall averages 23 inches (58.4 cm) a year, while in the lowlands of the west side, about 30 inches (76.2 cm) of precipitation fall in the average year. As moist air is forced up to the elevations of the Divide, it loses its moisture and precipitation jumps to 100 inches (2.5 m) or more in isolated mountain cirques. Snowfall settles to around a 16-foot (4.9 m) average snowpack. Early summer snow removal on Going-to-the-Sun Road, which crosses the Continental Divide, is so spectacular it has become a spectator sport (via Road Crew photos in the park flickr album).

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.

Climate Change

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.