Frost dates for St. John, WA
At St. John, the median last spring frost (32°F) is Apr 29 and the median first fall frost is Oct 4, for a typical growing season of 161 days. For a 90% chance that the last frost has passed, wait until May 15. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- Apr 29Last spring frost (median)50% chance of 32°F after this date
- May 15Safer planting date10% chance of 32°F after this date
- Oct 4First fall frost (median)50% chance of 32°F by this date
- 161 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 30 | May 16 | Jun 7 |
| 32°F | Apr 9 | Apr 29 | May 15 |
| 28°F | Mar 11 | Apr 5 | Apr 29 |
| 24°F | Feb 15 | Mar 11 | Apr 6 |
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 4 | Sep 23 | Oct 9 |
| 32°F | Sep 19 | Oct 4 | Oct 23 |
| 28°F | Oct 2 | Oct 20 | Nov 11 |
| 24°F | Oct 14 | Nov 2 | 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 | 98 days | 126 days | 153 days |
| 32°F | 134 days | 161 days | 186 days |
| 28°F | 168 days | 198 days | 230 days |
| 24°F | 207 days | 238 days | 274 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 |
|---|---|---|---|
| 99171 | 6b | -5 to 0°F | 5 km |
| 99176 | 6b | -5 to 0°F | 13 km |
| 99125 | 7a | 0 to 5°F | 19 km |
| 99174 | 6b | -5 to 0°F | 20 km |
| 99017 | 6b | -5 to 0°F | 25 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 USC00457267, at 47.0933, -117.5878, elevation 595 m (1,952 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 123.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Rosalia (23 km)
- Spokane 17 SSW (36 km)
- Lacrosse (38 km)
- Pullman 2 NW (48 km)
- Pullman Moscow Regional Airport (53 km)
- Spokane Intl Airport (59 km)
- Ritzville 1 SSE (59 km)
- Spokane WFO (65 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.