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Will it freeze in Hermiston in the next 7 nights?
No overnight lows at or below 32°F are forecast in Hermiston during the next 7 nights in the available NWS frost forecast.
Tonight: forecast low 34°F. Frost possible.
NWS forecast period: Thu, Nov 5, 6:00 PM PST to Fri, Nov 6, 6:00 AM PST.
2 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 34°F Frost possible · Mostly Clear
- Fri, Nov 6 38°F Above 36°F · Slight Chance Rain Showers then Mostly Cloudy
- Sat, Nov 7 40°F Above 36°F · Mostly Cloudy
- Sun, Nov 8 36°F Frost possible · Mostly Cloudy
- Mon, Nov 9 38°F Above 36°F · Partly Cloudy then Slight Chance Rain Showers
- Tue, Nov 10 42°F Above 36°F · Slight Chance Rain Showers
- Wed, Nov 11 41°F Above 36°F · Slight Chance Rain Showers then Mostly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Hermiston
The median first fall hard-freeze date (28°F) is October 24, from NOAA’s 1991–2020 Climate Normals at Hermiston Municipal Airport. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | Apr 26 · May 8 · May 22 | Sep 12 · Sep 28 · Oct 12 | 142 days |
| 32°F freeze | Apr 9 · Apr 26 · May 10 | Sep 25 · Oct 10 · Oct 26 | 167 days |
| 28°F hard freeze | Mar 20 · Apr 9 · Apr 29 | Oct 4 · Oct 24 · Nov 7 | 196 days |
Average high temperature by month
1991–2020 normals at Hermiston Municipal Airport
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Hermiston, OR come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Hermiston Municipal Airport (station USW00004113, elevation 641 ft), 1.2 mi from Hermiston. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Hermiston
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Umatilla, OR | 6.2 mi | Mar 30 | Nov 4 |
| Pendleton, OR | 25 mi | Apr 22 | Oct 9 |
| Kennewick, WA | 25 mi | Mar 28 | Oct 30 |
| Pasco, WA | 31 mi | Apr 27 | Oct 11 |
| Richland, WA | 31 mi | Apr 6 | Oct 24 |
| West Richland, WA | 34 mi | Apr 6 | Oct 24 |
| Prosser, WA | 35 mi | Apr 14 | Oct 22 |
| Grandview, WA | 41 mi | May 1 | Oct 6 |
| Milton-Freewater, OR | 43 mi | Mar 25 | Oct 29 |
| College Place, WA | 45 mi | May 2 | Oct 1 |
Frequently asked questions
When is the last frost in Hermiston?
On average, the last spring frost (32°F) in Hermiston is around April 26. In about 1 year in 10 it comes after May 10, and in 9 years in 10 it comes after April 9.
When is the first frost in Hermiston?
The first fall frost (32°F) usually arrives around October 10. There’s a 10% chance of a freeze by September 25 and a 90% chance by October 26.
Can it frost in Hermiston after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after May 8.
What growing zone is Hermiston?
Hermiston is in USDA Plant Hardiness Zone 7b (average annual extreme minimum temperature 5 to 10°F), based on the 2023 USDA map for ZIP code 97838. See growing zones in Oregon.
More: all Oregon frost dates · Oregon growing zones · frost vs. freeze