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Frost dates for Riverton, Wyoming

In a typical year, Riverton’s last spring frost lands around May 12 and the first fall frost around Sep 24, a growing season of about 135 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 Riverton, Wyoming
OddsLast spring frostFirst fall frost
10 percentMay 1Sep 11
50 percentMay 12Sep 24
90 percentMay 26Oct 7

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 Riverton is typically around 43°F at 4 inches this time of year, estimated from the last two weeks of normal air temperatures.

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Common questions

When is the last frost in Riverton, Wyoming?

Riverton’s last spring frost falls around May 12 in a typical year. One year in ten it is done by May 1, and one year in ten frost holds on until May 26. Frost-sensitive planting usually waits for the late side of that band.

When is the first fall frost in Riverton?

The first fall frost arrives around September 24 in a typical year, as early as September 11 in an early year and as late as October 7 in a late one.

How long is the growing season in Riverton?

About 135 days, counted between the typical last spring frost and the typical first fall frost.

What USDA zone is Riverton in?

Riverton 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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