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Frost dates for Casper, Wyoming

In a typical year, Casper’s last spring frost lands around May 10 and the first fall frost around Sep 29, a growing season of about 142 days. These are odds drawn from 30-year NOAA climate normals, not a promise. USDA zone 5a.

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

Last spring frost and first fall frost odds for Casper, Wyoming
OddsLast spring frostFirst fall frost
10 percentApr 30Sep 14
50 percentMay 10Sep 29
90 percentMay 24Oct 12

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 Casper 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 Casper, Wyoming?

Casper’s last spring frost falls around May 10 in a typical year. One year in ten it is done by April 30, and one year in ten frost holds on until May 24. Frost-sensitive planting usually waits for the late side of that band.

When is the first fall frost in Casper?

The first fall frost arrives around September 29 in a typical year, as early as September 14 in an early year and as late as October 12 in a late one.

How long is the growing season in Casper?

About 142 days, counted between the typical last spring frost and the typical first fall frost.

What USDA zone is Casper in?

Casper is in USDA hardiness zone 5a 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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