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Frost dates for Fort Collins, Colorado

In a typical year, Fort Collins’s last spring frost lands around May 2 and the first fall frost around Oct 7, a growing season of about 158 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 5b.

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

Last spring frost and first fall frost odds for Fort Collins, Colorado
OddsLast spring frostFirst fall frost
10 percentApr 18Sep 24
50 percentMay 2Oct 7
90 percentMay 14Oct 20

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 Fort Collins is typically around 49°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 Fort Collins, Colorado?

Fort Collins’s last spring frost falls around May 2 in a typical year. One year in ten it is done by April 18, and one year in ten frost holds on until May 14. Frost-sensitive planting usually waits for the late side of that band.

When is the first fall frost in Fort Collins?

The first fall frost arrives around October 7 in a typical year, as early as September 24 in an early year and as late as October 20 in a late one.

How long is the growing season in Fort Collins?

About 158 days, counted between the typical last spring frost and the typical first fall frost.

What USDA zone is Fort Collins in?

Fort Collins is in USDA hardiness zone 5b 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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