Frost dates for Petersburg 1, AK
At Petersburg 1, the median last spring frost (32°F) is Apr 29 and the median first fall frost is Oct 17, for a typical growing season of 169 days. For a 90% chance that the last frost has passed, wait until May 14. Nearby ZIP codes are in USDA hardiness zone 7b.
- Apr 29Last spring frost (median)50% chance of 32°F after this date
- May 14Safer planting date10% chance of 32°F after this date
- Oct 17First fall frost (median)50% chance of 32°F by this date
- 169 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 14 | May 29 |
| 32°F | Apr 15 | Apr 29 | May 14 |
| 28°F | Mar 26 | Apr 11 | Apr 30 |
| 24°F | Mar 2 | Mar 25 | Apr 10 |
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 16 | Oct 1 | Oct 17 |
| 32°F | Sep 30 | Oct 17 | Nov 1 |
| 28°F | Oct 14 | Nov 1 | Nov 20 |
| 24°F | Oct 30 | Nov 17 | Dec 8 |
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 | 116 days | 138 days | 159 days |
| 32°F | 145 days | 169 days | 189 days |
| 28°F | 177 days | 204 days | 229 days |
| 24°F | 213 days | 240 days | 271 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 |
|---|---|---|---|
| 99833 | 7b | 5 to 10°F | 16 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 USW00025329, at 56.8056, -132.9372, elevation 33 m (107 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 115.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Wrangell Airport (50 km)
- Point Baker (66 km)
- Little Port Walter (115 km)
- Port Alexander (122 km)
- Hidden Falls Hatchery (126 km)
- Thorne Bay (126 km)
- Klawock Airport (137 km)
- Sitka 1 NE (148 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.