Frost dates for Sitka Airport, AK
At Sitka Airport, the median last spring frost (32°F) is Apr 12 and the median first fall frost is Nov 1, for a typical growing season of 201 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zones 7a to 8a.
- Apr 12Last spring frost (median)50% chance of 32°F after this date
- Apr 30Safer planting date10% chance of 32°F after this date
- Nov 1First fall frost (median)50% chance of 32°F by this date
- 201 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 18 | May 2 | May 18 |
| 32°F | Mar 28 | Apr 12 | Apr 30 |
| 28°F | Mar 6 | Mar 24 | Apr 7 |
| 24°F | Jan 29 | Mar 7 | Mar 25 |
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 29 | Oct 15 | Nov 1 |
| 32°F | Oct 13 | Nov 1 | Nov 21 |
| 28°F | Nov 1 | Nov 22 | Dec 17 |
| 24°F | Nov 15 | Dec 9 | 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 | 139 days | 164 days | 186 days |
| 32°F | 174 days | 201 days | 228 days |
| 28°F | 215 days | 242 days | 273 days |
| 24°F | 247 days | 280 days | 319 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 99% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99835 | 7b | 5 to 10°F | 22 km |
| 99820 | 7a | 0 to 5°F | 75 km |
| 99830 | 7b | 5 to 10°F | 83 km |
| 99836 | 8a | 10 to 15°F | 99 km |
| 99841 | 7a | 0 to 5°F | 101 km |
| 99829 | 7a | 0 to 5°F | 109 km |
| 99832 | 7a | 0 to 5°F | 111 km |
| 99825 | 7a | 0 to 5°F | 128 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 USW00025333, at 57.0481, -135.3647, elevation 4 m (14 ft).
- Data quality: Standard (24+ years of data), 28 years of freeze data.
- Average days per year at or below 32°F: 70.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sitka 1 NE (3 km)
- Hidden Falls Hatchery (35 km)
- Little Port Walter (86 km)
- Port Alexander (99 km)
- Pelican (113 km)
- Hoonah (118 km)
- Point Baker (131 km)
- Elfin Cove (140 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.