Frost dates for Hidden Falls Hatchery, AK
At Hidden Falls Hatchery, the median last spring frost (32°F) is Apr 29 and the median first fall frost is Oct 25, for a typical growing season of 176 days. For a 90% chance that the last frost has passed, wait until May 15. Nearby ZIP codes are in USDA hardiness zone 7a.
- Apr 29Last spring frost (median)50% chance of 32°F after this date
- May 15Safer planting date10% chance of 32°F after this date
- Oct 25First fall frost (median)50% chance of 32°F by this date
- 176 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 15 |
| 28°F | Mar 22 | Apr 10 | Apr 29 |
| 24°F | Feb 28 | Mar 24 | Apr 11 |
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 22 | Oct 9 | Oct 25 |
| 32°F | Oct 7 | Oct 25 | Nov 10 |
| 28°F | Oct 22 | Nov 9 | Dec 1 |
| 24°F | Nov 4 | Nov 24 | Dec 24 |
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 | 122 days | 146 days | 168 days |
| 32°F | 154 days | 176 days | 199 days |
| 28°F | 186 days | 212 days | 241 days |
| 24°F | 215 days | 245 days | 280 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 |
|---|---|---|---|
| 99820 | 7a | 0 to 5°F | 40 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 USC00503605, at 57.2178, -134.8770, elevation 7 m (22 ft).
- Data quality: Representative (10+ years), 12 years of freeze data.
- Average days per year at or below 32°F: 120.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sitka 1 NE (32 km)
- Sitka Airport (35 km)
- Little Port Walter (94 km)
- Hoonah (104 km)
- Port Alexander (109 km)
- Pelican (115 km)
- Eaglecrest Base (120 km)
- Point Baker (123 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.