Frost dates for Newhalem, WA
At Newhalem, the median last spring frost (32°F) is Apr 2 and the median first fall frost is Nov 14, for a typical growing season of 224 days. For a 90% chance that the last frost has passed, wait until Apr 27. Nearby ZIP codes are in USDA hardiness zone 7a.
- Apr 2Last spring frost (median)50% chance of 32°F after this date
- Apr 27Safer planting date10% chance of 32°F after this date
- Nov 14First 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 10 | Apr 27 | May 14 |
| 32°F | Mar 9 | Apr 2 | Apr 27 |
| 28°F | Jan 24 | Mar 2 | Mar 25 |
| 24°F | Dec 24 | Jan 31 | Mar 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 | Oct 18 | Oct 30 | Nov 14 |
| 32°F | Oct 28 | Nov 14 | Dec 5 |
| 28°F | Nov 12 | Dec 4 | Jan 7 |
| 24°F | Nov 24 | Dec 22 | Jan 30 |
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 | 163 days | 184 days | 208 days |
| 32°F | 194 days | 224 days | 257 days |
| 28°F | 244 days | 277 days | 318 days |
| 24°F | 280 days | 320 days | 364 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 99% |
| 24°F | 89% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 98283 | 7a | 0 to 5°F | 15 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 USC00455840, at 48.6758, -121.2419, elevation 160 m (525 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 58.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Diablo Dam (8 km)
- Ross Dam (14 km)
- Darrington 21 NNE (21 km)
- Upper Baker Dam (33 km)
- Concrete Ppl Fish Station (40 km)
- Stehekin 4 NW (52 km)
- Darrington Ranger Station (53 km)
- Mazama (60 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.