When is the last frost in Sumpter, OR?

Frost is possible in any month at the nearest NOAA station (Austin 3 S, OR), so there is no reliable average last frost date.

When is the first frost in Sumpter, OR?

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 97877Sumpter, OR

Frost is possible in any month near Sumpter, based on NOAA 1991-2020 records for the Austin 3 S, OR 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)	—	—	39 days	100%
Frost / freeze (32°F)	—	—	74 days	100%
Hard freeze (28°F)	May 7 · May 23 · Jun 13	Aug 31 · Sep 17 · Oct 3	115 days	100%

Where these dates come from

ZIP code 97877 is matched to the NOAA station Austin 3 S, OR, 29.7 km away, at 4,213 ft elevation (213 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Austin 3 S, OR (used)	4,213 ft	—	—
Baker City Muni Ap, OR	3,361 ft	May 25	Sep 15
Union, OR	2,777 ft	May 11	Sep 26
La Grande, OR	2,755 ft	May 6	Oct 1

Frost dates near Sumpter

Haines, OR 97833 · last May 25, first Sep 15
Hereford, OR 97837 · last —, first —
Baker City, OR 97814 · last May 25, first Sep 15
Unity, OR 97884 · last —, first —
Bates, OR 97817 · last —, first —
North Powder, OR 97867 · last May 25, first Sep 15
Bridgeport, OR 97819 · last May 25, first Sep 15
Prairie City, OR 97869 · last May 28, first Sep 18

Frequently asked questions

When is the last frost in Sumpter, OR?: Frost is possible in any month at the nearest NOAA station (Austin 3 S, OR), so there is no reliable average last frost date.
When is the first frost in Sumpter, OR?: 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.