Frost dates for Sedro-Woolley, WA
At Sedro-Woolley, the median last spring frost (32°F) is Mar 27 and the median first fall frost is Nov 6, for a typical growing season of 224 days. For a 90% chance that the last frost has passed, wait until Apr 17. Nearby ZIP codes are in USDA hardiness zones 8a to 8b.
- Mar 27Last spring frost (median)50% chance of 32°F after this date
- Apr 17Safer planting date10% chance of 32°F after this date
- Nov 6First fall frost (median)50% chance of 32°F by this date
- 224 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 1 | Apr 22 | May 11 |
| 32°F | Mar 8 | Mar 27 | Apr 17 |
| 28°F | Feb 2 | Mar 1 | Mar 22 |
| 24°F | Dec 25 | Feb 4 | Mar 2 |
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 1 | Oct 17 | Nov 8 |
| 32°F | Oct 15 | Nov 6 | Nov 28 |
| 28°F | Nov 1 | Nov 24 | Dec 19 |
| 24°F | Nov 18 | Dec 11 | Jan 14 |
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 | 149 days | 178 days | 204 days |
| 32°F | 195 days | 224 days | 253 days |
| 28°F | 235 days | 268 days | 302 days |
| 24°F | 275 days | 312 days | 354 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 96% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 98235 | 8b | 15 to 20°F | 4 km |
| 98284 | 8b | 15 to 20°F | 9 km |
| 98263 | 8b | 15 to 20°F | 13 km |
| 98255 | 8b | 15 to 20°F | 18 km |
| 98220 | 8a | 10 to 15°F | 21 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 USC00457507, at 48.4958, -122.2355, elevation 18 m (60 ft).
- Data quality: Representative (10+ years), 20 years of freeze data.
- Average days per year at or below 32°F: 46.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Mount Vernon 3 WNW (13 km)
- Anacortes (28 km)
- Bellingham 3 SSW (32 km)
- Arlington (34 km)
- Whidbey Island NAS (36 km)
- Concrete Ppl Fish Station (37 km)
- Bellingham Intl Airport (40 km)
- Upper Baker Dam (44 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.