Frost dates for Seattle Tacoma Intl Airport, WA
At Seattle Tacoma Intl Airport, the median last spring frost (32°F) is Mar 2 and the median first fall frost is Nov 23, for a typical growing season of 266 days. For a 90% chance that the last frost has passed, wait until Mar 23. Nearby ZIP codes are in USDA hardiness zone 9a.
- Mar 2Last spring frost (median)50% chance of 32°F after this date
- Mar 23Safer planting date10% chance of 32°F after this date
- Nov 23First fall frost (median)50% chance of 32°F by this date
- 266 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 | Mar 13 | Mar 31 | Apr 21 |
| 32°F | Feb 5 | Mar 2 | Mar 23 |
| 28°F | Dec 20 | Feb 4 | Feb 28 |
| 24°F | Dec 5 | Jan 4 | Feb 17 |
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 24 | Nov 7 | Nov 23 |
| 32°F | Nov 6 | Nov 23 | Dec 15 |
| 28°F | Nov 17 | Dec 10 | Jan 16 |
| 24°F | Nov 26 | Dec 17 | Feb 1 |
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 | 195 days | 219 days | 244 days |
| 32°F | 239 days | 266 days | 298 days |
| 28°F | 277 days | 315 days | 352 days |
| 24°F | 316 days | 355 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 95% |
| 24°F | 64% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 98158 | 9a | 20 to 25°F | 1 km |
| 98148 | 9a | 20 to 25°F | 1 km |
| 98166 | 9a | 20 to 25°F | 3 km |
| 98188 | 9a | 20 to 25°F | 3 km |
| 98198 | 9a | 20 to 25°F | 6 km |
| 98070 | 9a | 20 to 25°F | 13 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 USW00024233, at 47.4444, -122.3139, elevation 113 m (370 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 25.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Kent (6 km)
- Renton Muni Airport (9 km)
- Seattle Boeing Field (10 km)
- Tacoma #1 (23 km)
- Seattle Sand Point Wsfo (27 km)
- Landsburg (28 km)
- Tacoma Narrows Airport (28 km)
- Bremerton (31 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.