Frost dates for Coulee Dam 1 SW, WA
At Coulee Dam 1 SW, the median last spring frost (32°F) is Apr 22 and the median first fall frost is Oct 21, for a typical growing season of 180 days. For a 90% chance that the last frost has passed, wait until May 7. Nearby ZIP codes are in USDA hardiness zones 6b to 7b.
- Apr 22Last spring frost (median)50% chance of 32°F after this date
- May 7Safer planting date10% chance of 32°F after this date
- Oct 21First fall frost (median)50% chance of 32°F by this date
- 180 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 21 | May 5 | May 21 |
| 32°F | Apr 5 | Apr 22 | May 7 |
| 28°F | Mar 14 | Apr 1 | Apr 19 |
| 24°F | Feb 28 | Mar 13 | Apr 2 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 27 | Oct 8 | Oct 24 |
| 32°F | Oct 6 | Oct 21 | Nov 5 |
| 28°F | Oct 18 | Nov 1 | Nov 17 |
| 24°F | Oct 28 | Nov 13 | Nov 29 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 136 days | 156 days | 173 days |
| 32°F | 161 days | 180 days | 202 days |
| 28°F | 189 days | 214 days | 236 days |
| 24°F | 220 days | 243 days | 267 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99124 | 7b | 5 to 10°F | 6 km |
| 99116 | 7a | 0 to 5°F | 8 km |
| 99123 | 7a | 0 to 5°F | 9 km |
| 99133 | 7a | 0 to 5°F | 12 km |
| 99140 | 7a | 0 to 5°F | 32 km |
| 99155 | 6b | -5 to 0°F | 40 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00451767, at 47.9544, -118.9997, elevation 524 m (1,719 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 120.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Wilbur (29 km)
- Hartline (31 km)
- Chief Joseph Dam (49 km)
- Omak Airport (68 km)
- Davenport (71 km)
- Odessa (73 km)
- Chelan (76 km)
- Harrington (77 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.