Frost dates for Dayton 1 WSW, WA
At Dayton 1 WSW, the median last spring frost (32°F) is Apr 28 and the median first fall frost is Oct 13, for a typical growing season of 168 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zones 7a to 7b.
- Apr 28Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 13First fall frost (median)50% chance of 32°F by this date
- 168 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 28 | May 12 | Jun 3 |
| 32°F | Apr 11 | Apr 28 | May 14 |
| 28°F | Mar 15 | Apr 6 | Apr 28 |
| 24°F | Feb 19 | Mar 11 | Apr 3 |
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 14 | Oct 1 | Oct 15 |
| 32°F | Sep 30 | Oct 13 | Oct 29 |
| 28°F | Oct 9 | Oct 25 | Nov 12 |
| 24°F | Oct 18 | Nov 6 | Nov 30 |
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 | 112 days | 138 days | 161 days |
| 32°F | 147 days | 168 days | 190 days |
| 28°F | 176 days | 203 days | 231 days |
| 24°F | 209 days | 239 days | 269 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 |
|---|---|---|---|
| 99328 | 7a | 0 to 5°F | 11 km |
| 99361 | 7a | 0 to 5°F | 14 km |
| 99359 | 7b | 5 to 10°F | 25 km |
| 99348 | 7a | 0 to 5°F | 35 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 USC00452030, at 46.3153, -118.0022, elevation 475 m (1,557 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 113.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Walla Walla Regional Airport (33 km)
- Pomeroy (36 km)
- Whitman Mission (47 km)
- Lacrosse (56 km)
- Hatton 9 SE (67 km)
- Ice Harbor Dam (68 km)
- Connell 1 W (78 km)
- Pullman 2 NW (80 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.