Frost dates for Walla Walla Regional Airport, WA
At Walla Walla Regional Airport, the median last spring frost (32°F) is Mar 27 and the median first fall frost is Oct 31, for a typical growing season of 219 days. For a 90% chance that the last frost has passed, wait until Apr 22. Nearby ZIP codes are in USDA hardiness zone 7a.
- Mar 27Last spring frost (median)50% chance of 32°F after this date
- Apr 22Safer planting date10% chance of 32°F after this date
- Oct 31First fall frost (median)50% chance of 32°F by this date
- 219 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 2 | Apr 21 | May 8 |
| 32°F | Mar 3 | Mar 27 | Apr 22 |
| 28°F | Feb 9 | Mar 4 | Mar 27 |
| 24°F | Jan 10 | Feb 18 | Mar 10 |
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 | Oct 4 | Oct 19 | Nov 2 |
| 32°F | Oct 15 | Oct 31 | Nov 17 |
| 28°F | Oct 25 | Nov 14 | Dec 4 |
| 24°F | Nov 3 | Nov 28 | Dec 21 |
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 | 155 days | 180 days | 205 days |
| 32°F | 189 days | 219 days | 246 days |
| 28°F | 225 days | 253 days | 287 days |
| 24°F | 250 days | 287 days | 322 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 99% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99362 | 7a | 0 to 5°F | 2 km |
| 99329 | 7a | 0 to 5°F | 12 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 USW00024160, at 46.0947, -118.2869, elevation 355 m (1,166 ft).
- Data quality: Standard (24+ years of data), 25 years of freeze data.
- Average days per year at or below 32°F: 70.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Whitman Mission (15 km)
- Dayton 1 WSW (33 km)
- Ice Harbor Dam (49 km)
- Kennewick (64 km)
- Pasco Tri Cities Airport (67 km)
- Pomeroy (68 km)
- Sagemoor (69 km)
- Eltopia 8 WSW (75 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.