When is the last frost in Opal, WY?

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

When is the first frost in Opal, 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 83124Opal, WY

Frost is possible in any month near Opal, based on NOAA 1991-2020 records for the Fontenelle Dam, 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)	—	—	43 days	100%
Frost / freeze (32°F)	—	—	69 days	100%
Hard freeze (28°F)	May 19 · Jun 8 · Jun 29	Aug 28 · Sep 11 · Sep 25	95 days	100%

Where these dates come from

ZIP code 83124 is matched to the NOAA station Fontenelle Dam, WY, 29.1 km away, at 6,485 ft elevation (129 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Fontenelle Dam, WY (used)	6,485 ft	—	—
Kemmerer 2N, WY	6,937 ft	—	—
Fossil Butte, WY	6,785 ft	—	—
Church Buttes Gas Plt, WY	7,079 ft	May 25	Sep 27

Frost dates near Opal

Kemmerer, WY 83101 · last —, first —
Diamondville, WY 83116 · last —, first —
Frontier, WY 83121 · last —, first —
Granger, WY 82934 · last May 24, first Sep 22
Little America, WY 82929 · last May 24, first Sep 22
Lyman, WY 82937 · last Jun 14, first Sep 9
Fort Bridger, WY 82933 · last Jun 14, first Sep 9
La Barge, WY 83123 · last Jun 9, first Sep 4

Frequently asked questions

When is the last frost in Opal, WY?: Frost is possible in any month at the nearest NOAA station (Fontenelle Dam, WY), so there is no reliable average last frost date.
When is the first frost in Opal, 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.