When is the last frost in Boulder, WY?

Frost is possible in any month at the nearest NOAA station (Boulder Rearing Stn, WY), so there is no reliable average last frost date.

When is the first frost in Boulder, WY?

Frost is possible in any month at the nearest NOAA station.

Are these frost dates a forecast?

No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.

Frost dates for 82923Boulder, WY

Frost is possible in any month near Boulder, based on NOAA 1991-2020 records for the Boulder Rearing Stn, WY station.

Frost is possible in any month. Even summer nights can drop to freezing at this station, so protect tender plants whenever cold nights are forecast.

Frost risk by date

NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.

Spring dates: chance of a frost AFTER the date. Fall dates: chance of a frost BEFORE the date.
Temperature	Last spring: 90% / 50% / 10% chance	First fall: 10% / 50% / 90% chance	Growing season (50%)	Years with at least one
Light frost (36°F)	—	—	20 days	100%
Frost / freeze (32°F)	—	—	43 days	100%
Hard freeze (28°F)	May 30 · Jun 14 · Jul 5	Aug 15 · Aug 31 · Sep 13	74 days	100%

Where these dates come from

ZIP code 82923 is matched to the NOAA station Boulder Rearing Stn, WY, 12.6 km away, at 6,940 ft elevation (209 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Boulder Rearing Stn, WY (used)	6,940 ft	—	—
Pinedale, WY	7,210 ft	—	—
Big Piney Marbleton Ap, WY	6,970 ft	—	—
Cora, WY	7,347 ft	—	—

Frost dates near Boulder

Pinedale, WY 82941 · last —, first —
Big Piney, WY 83113 · last —, first —
Daniel, WY 83115 · last —, first —
Cora, WY 82925 · last —, first —
Fort Washakie, WY 82514 · last May 18, first Sep 27
Farson, WY 82932 · last —, first —
La Barge, WY 83123 · last Jun 9, first Sep 4
Crowheart, WY 82512 · last Jun 1, first Sep 14

Frequently asked questions

When is the last frost in Boulder, WY?: Frost is possible in any month at the nearest NOAA station (Boulder Rearing Stn, WY), so there is no reliable average last frost date.
When is the first frost in Boulder, WY?: Frost is possible in any month at the nearest NOAA station.
Are these frost dates a forecast?: No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.