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Frost dates for Great Falls, Montana

In a typical year, Great Falls’s last spring frost lands around May 6 and the first fall frost around Oct 1, a growing season of about 148 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 4b.

Right now the typical frost season has arrived; planting waits for spring.

Last spring frost and first fall frost odds for Great Falls, Montana
OddsLast spring frostFirst fall frost
10 percentApr 23Sep 17
50 percentMay 6Oct 1
90 percentMay 19Oct 16

A 10 percent year is an early year, a 90 percent year a late one. Frost-sensitive planting usually waits for the 90 percent side of the last-frost band.

Soil in Great Falls is typically around 46°F at 4 inches this time of year, estimated from the last two weeks of normal air temperatures.

See what is plantable in your ZIP with the what-to-plant lookup.

Common questions

When is the last frost in Great Falls, Montana?

Great Falls’s last spring frost falls around May 6 in a typical year. One year in ten it is done by April 23, and one year in ten frost holds on until May 19. Frost-sensitive planting usually waits for the late side of that band.

When is the first fall frost in Great Falls?

The first fall frost arrives around October 1 in a typical year, as early as September 17 in an early year and as late as October 16 in a late one.

How long is the growing season in Great Falls?

About 148 days, counted between the typical last spring frost and the typical first fall frost.

What USDA zone is Great Falls in?

Great Falls is in USDA hardiness zone 4b under the 2023 USDA Plant Hardiness Zone Map.

Dates come from 30-year NOAA climate normals for the nearest reporting station. They describe odds, not a forecast.

Nearby cities

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