Frost dates for Alyeska, AK
At Alyeska, the median last spring frost (32°F) is May 8 and the median first fall frost is Sep 29, for a typical growing season of 142 days. For a 90% chance that the last frost has passed, wait until May 22. Nearby ZIP codes are in USDA hardiness zone 5b.
- May 8Last spring frost (median)50% chance of 32°F after this date
- May 22Safer planting date10% chance of 32°F after this date
- Sep 29First fall frost (median)50% chance of 32°F by this date
- 142 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 | May 12 | May 24 | Jun 5 |
| 32°F | Apr 26 | May 8 | May 22 |
| 28°F | Apr 12 | Apr 26 | May 7 |
| 24°F | Mar 31 | Apr 12 | Apr 28 |
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 1 | Sep 17 | Sep 30 |
| 32°F | Sep 14 | Sep 29 | Oct 13 |
| 28°F | Sep 27 | Oct 11 | Oct 26 |
| 24°F | Oct 5 | Oct 21 | Nov 6 |
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 | 94 days | 113 days | 131 days |
| 32°F | 124 days | 142 days | 161 days |
| 28°F | 149 days | 169 days | 189 days |
| 24°F | 171 days | 192 days | 212 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 |
|---|---|---|---|
| 99540 | 5b | -15 to -10°F | 13 km |
| 99587 | 5b | -15 to -10°F | 13 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 USC00500243, at 60.9583, -149.1108, elevation 83 m (272 ft).
- Data quality: Standard (24+ years of data), 29 years of freeze data.
- Average days per year at or below 32°F: 175.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Portage Glacier V C (24 km)
- Hope (29 km)
- Whittier (31 km)
- Eagle River Nature Center (32 km)
- Glen Alps (35 km)
- Anchorage Upper De Armoun (36 km)
- Anchorage Rabbit Creek #2 (38 km)
- Eagle River 5 SE (42 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.