When is the last frost in Lemhi, ID?

For ZIP code 83465, the average last spring frost (32°F) is June 12, based on NOAA 1991-2020 climate normals for the May 2Sse, ID weather station. There is a 1-in-10 chance of a frost after June 29.

When is the first frost in Lemhi, ID?

The average first fall frost (32°F) is September 6. There is a 1-in-10 chance of frost by August 23, so tender plants are at risk from that point on.

How long is the growing season in 83465?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 85 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 83465Lemhi, ID

The average last spring frost in Lemhi is June 12 and the average first fall frost is September 6, giving a typical growing season of about 85 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jun 12
Average first fall frost: Sep 6
Growing season: 85 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)	—	—	54 days	100%
Frost / freeze (32°F)	May 24 · Jun 12 · Jun 29	Aug 23 · Sep 6 · Sep 20	85 days	100%
Hard freeze (28°F)	May 7 · May 20 · Jun 11	Sep 3 · Sep 19 · Oct 3	118 days	100%

Where these dates come from

ZIP code 83465 is matched to the NOAA station May 2Sse, ID, 38.5 km away, at 5,050 ft elevation (140 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
May 2Sse, ID (used)	5,050 ft	Jun 12	Sep 6
Leadore #2, ID	6,000 ft	—	—
Salmon-Ksra, ID	3,953 ft	May 17	Sep 24
Dillon 18 Wsw, MT	5,971 ft	—	—

Frost dates near Lemhi

Leadore, ID 83464 · last —, first —
Tendoy, ID 83468 · last —, first —
May, ID 83253 · last Jun 12, first Sep 6
Ellis, ID 83235 · last Jun 12, first Sep 6
Salmon, ID 83467 · last May 17, first Sep 24
Carmen, ID 83462 · last May 17, first Sep 24
Cobalt, ID 83229 · last May 14, first Sep 25
Challis, ID 83226 · last May 14, first Sep 25

Frequently asked questions

When is the last frost in Lemhi, ID?: For ZIP code 83465, the average last spring frost (32°F) is June 12, based on NOAA 1991-2020 climate normals for the May 2Sse, ID weather station. There is a 1-in-10 chance of a frost after June 29.
When is the first frost in Lemhi, ID?: The average first fall frost (32°F) is September 6. There is a 1-in-10 chance of frost by August 23, so tender plants are at risk from that point on.
How long is the growing season in 83465?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 85 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.