Frost dates for Clear Sky, AK
At Clear Sky, the median last spring frost (32°F) is May 24 and the median first fall frost is Sep 4, for a typical growing season of 100 days. For a 90% chance that the last frost has passed, wait until Jun 12. Nearby ZIP codes are in USDA hardiness zone 2a.
- May 24Last spring frost (median)50% chance of 32°F after this date
- Jun 12Safer planting date10% chance of 32°F after this date
- Sep 4First fall frost (median)50% chance of 32°F by this date
- 100 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 |
|---|---|---|---|
| 32°F | May 11 | May 24 | Jun 12 |
| 28°F | May 2 | May 11 | May 26 |
| 24°F | Apr 23 | May 4 | May 16 |
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 |
|---|---|---|---|
| 32°F | Aug 19 | Sep 4 | Sep 18 |
| 28°F | Sep 1 | Sep 15 | Sep 29 |
| 24°F | Sep 11 | Sep 26 | Oct 7 |
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 | 46 days | 74 days | 96 days |
| 32°F | 76 days | 100 days | 121 days |
| 28°F | 104 days | 124 days | 143 days |
| 24°F | 126 days | 144 days | 159 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 |
|---|---|---|---|
| 99704 | 2a | -50 to -45°F | 5 km |
| 99744 | 2a | -50 to -45°F | 11 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 USC00502015, at 64.2453, -149.1828, elevation 197 m (646 ft).
- Data quality: Representative (10+ years), 11 years of freeze data.
- Average days per year at or below 32°F: 234.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Kobe Hill (13 km)
- Nenana Muni Airport (34 km)
- Healy (43 km)
- McKinley Park (60 km)
- Keystone Ridge (86 km)
- Ester (87 km)
- Fairbanks Intl Airport (88 km)
- Fairbanks Airport #2 (89 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.