When is the last frost in Asotin, WA?

For ZIP code 99402, the average last spring frost (32°F) is June 8, based on NOAA 1991-2020 climate normals for the Enterprise 20 Nne, OR weather station. There is a 1-in-10 chance of a frost after July 8.

When is the first frost in Asotin, WA?

The average first fall frost (32°F) is September 5. There is a 1-in-10 chance of frost by August 16, so tender plants are at risk from that point on.

How long is the growing season in 99402?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 84 days long.

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 99402Asotin, WA

The average last spring frost in Asotin is June 8 and the average first fall frost is September 5, giving a typical growing season of about 84 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jun 8
Average first fall frost: Sep 5
Growing season: 84 days

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)	—	—	46 days	100%
Frost / freeze (32°F)	May 18 · Jun 8 · Jul 8	Aug 16 · Sep 5 · Sep 22	84 days	100%
Hard freeze (28°F)	Apr 28 · May 13 · Jun 5	Sep 3 · Sep 22 · Oct 9	126 days	100%

Where these dates come from

ZIP code 99402 is matched to the NOAA station Enterprise 20 Nne, OR, 48.8 km away, at 3,280 ft elevation (304 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Enterprise 20 Nne, OR (used)	3,280 ft	Jun 8	Sep 5
Lewiston Nez Perce Co Ap, ID	1,436 ft	Apr 6	Oct 26
Winchester, ID	3,972 ft	May 23	Sep 25
Cottonwood 2 Wsw, ID	3,945 ft	May 6	Oct 13

Frost dates near Asotin

Anatone, WA 99401 · last Jun 8, first Sep 5
Lewiston, ID 83501 · last Apr 6, first Oct 26
Clarkston, WA 99403 · last Apr 6, first Oct 26
Winchester, ID 83555 · last May 23, first Sep 25
Lapwai, ID 83540 · last Apr 6, first Oct 26
Culdesac, ID 83524 · last Apr 6, first Oct 26
Reubens, ID 83548 · last May 24, first Sep 20
Craigmont, ID 83523 · last May 23, first Sep 25

Frequently asked questions

When is the last frost in Asotin, WA?: For ZIP code 99402, the average last spring frost (32°F) is June 8, based on NOAA 1991-2020 climate normals for the Enterprise 20 Nne, OR weather station. There is a 1-in-10 chance of a frost after July 8.
When is the first frost in Asotin, WA?: The average first fall frost (32°F) is September 5. There is a 1-in-10 chance of frost by August 16, so tender plants are at risk from that point on.
How long is the growing season in 99402?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 84 days long.
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.