When is the last frost in Imnaha, OR?

For ZIP code 97842, 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 Imnaha, OR?

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 97842?

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 97842Imnaha, OR

The average last spring frost in Imnaha 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 97842 is matched to the NOAA station Enterprise 20 Nne, OR, 33.4 km away, at 3,280 ft elevation (428 ft lower 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
Joseph, OR	4,184 ft	May 24	Oct 1
Riggins, ID	2,056 ft	May 6	Oct 9
Wallowa, OR	2,923 ft	Jun 7	Sep 9

Frost dates near Imnaha

Joseph, OR 97846 · last May 24, first Oct 1
Enterprise, OR 97828 · last May 24, first Oct 1
Riggins, ID 83549 · last —, first —
Pollock, ID 83547 · last May 6, first Oct 9
Lucile, ID 83542 · last May 9, first Oct 3
Lostine, OR 97857 · last Jun 7, first Sep 9
White Bird, ID 83554 · last May 6, first Oct 9
Wallowa, OR 97885 · last Jun 7, first Sep 9

Frequently asked questions

When is the last frost in Imnaha, OR?: For ZIP code 97842, 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 Imnaha, OR?: 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 97842?: 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.