Fall foliage in Montana

Montana’s fall is short and most of the state changes within about two weeks. Aspen and cottonwood in Glacier National Park, along Going-to-the-Sun Road and around Swiftcurrent and Avalanche lakes turn in the first ten days of October, and western larch on the slopes above Whitefish, Swan Lake and the Flathead goes gold over the same period. The valleys follow within days. Larch is a deciduous conifer, and its yellow on otherwise evergreen mountainsides is what distinguishes Montana’s autumn.

Those are the months when color is present somewhere in Montana, from its highest ground to its lowest. Any one location changes over a much shorter period than that.

Why the timing shifts from year to year

Shortening days start the process, so most places in Montana change at close to their usual time each year. Within the state, elevation and latitude account for most of the difference: higher and more northern ground generally changes first, and lower, sheltered ground last. Weather has more effect on how strong the color is than on when it appears. Cool nights and sunny days favor the reds, a dry summer mutes them, and a hard freeze or a windstorm can strip a slope in a day. What determines the timing goes through this in detail.

Nearby states

Fall color does not follow state lines. Montana borders:

• Idaho fall foliage
• North Dakota fall foliage
• South Dakota fall foliage
• Wyoming fall foliage

Timing for a specific place

This page describes a whole state, which is about as precise as a season can be described in words. Conditions at one overlook on one weekend are a narrower question, and that is the one Fallcast answers: an expected period of color for a specific location, with a confidence attached, updated through the season as the trees change. It is coming to iPhone this fall.

Questions, or somewhere in Montana you would like covered? Write to fallcastapp@gmail.com.