Frost dates for Seattle Boeing Field, WA
At Seattle Boeing Field, the median last spring frost (32°F) is Mar 13 and the median first fall frost is Nov 17, for a typical growing season of 247 days. For a 90% chance that the last frost has passed, wait until Apr 1. Nearby ZIP codes are in USDA hardiness zone 9a.
- Mar 13Last spring frost (median)50% chance of 32°F after this date
- Apr 1Safer planting date10% chance of 32°F after this date
- Nov 17First fall frost (median)50% chance of 32°F by this date
- 247 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 17 | Apr 3 | Apr 28 |
| 32°F | Feb 20 | Mar 13 | Apr 1 |
| 28°F | Jan 7 | Feb 18 | Mar 10 |
| 24°F | Dec 7 | Jan 17 | Feb 23 |
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 17 | Oct 31 | Nov 17 |
| 32°F | Nov 1 | Nov 17 | Dec 6 |
| 28°F | Nov 12 | Dec 2 | Dec 30 |
| 24°F | Nov 21 | Dec 14 | Jan 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 | 182 days | 209 days | 232 days |
| 32°F | 222 days | 247 days | 278 days |
| 28°F | 260 days | 295 days | 334 days |
| 24°F | 300 days | 337 days | 365 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 98% |
| 24°F | 81% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 98108 | 9a | 20 to 25°F | 1 km |
| 98118 | 9a | 20 to 25°F | 3 km |
| 98106 | 9a | 20 to 25°F | 4 km |
| 98168 | 9a | 20 to 25°F | 5 km |
| 98146 | 9a | 20 to 25°F | 6 km |
| 98126 | 9a | 20 to 25°F | 6 km |
| 98144 | 9a | 20 to 25°F | 6 km |
| 98134 | 9a | 20 to 25°F | 6 km |
| 98040 | 9a | 20 to 25°F | 6 km |
| 98136 | 9a | 20 to 25°F | 7 km |
| 98104 | 9a | 20 to 25°F | 8 km |
| 98174 | 9a | 20 to 25°F | 9 km |
| 98164 | 9a | 20 to 25°F | 9 km |
| 98154 | 9a | 20 to 25°F | 9 km |
| 98122 | 9a | 20 to 25°F | 9 km |
| 98116 | 9a | 20 to 25°F | 9 km |
| 98101 | 9a | 20 to 25°F | 9 km |
| 98121 | 9a | 20 to 25°F | 10 km |
| 98353 | 9a | 20 to 25°F | 14 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 USW00024234, at 47.5303, -122.3008, elevation 6 m (20 ft).
- Data quality: Representative (10+ years), 18 years of freeze data.
- Average days per year at or below 32°F: 30.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Renton Muni Airport (8 km)
- Seattle Tacoma Intl Airport (10 km)
- Kent (13 km)
- Seattle Sand Point Wsfo (18 km)
- Bremerton (29 km)
- Landsburg (31 km)
- Tacoma #1 (33 km)
- Snoqualmie Falls (35 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.