Frost dates for Sterling 6sw, AK
At Sterling 6sw, the median last spring frost (32°F) is May 20 and the median first fall frost is Sep 21, for a typical growing season of 123 days. For a 90% chance that the last frost has passed, wait until Jun 1. Nearby ZIP codes are in USDA hardiness zones 4b to 5a.
- May 20Last spring frost (median)50% chance of 32°F after this date
- Jun 1Safer planting date10% chance of 32°F after this date
- Sep 21First fall frost (median)50% chance of 32°F by this date
- 123 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 25 | Jun 4 | Jun 15 |
| 32°F | May 6 | May 20 | Jun 1 |
| 28°F | Apr 19 | May 3 | May 17 |
| 24°F | Apr 7 | Apr 19 | May 2 |
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 | Aug 26 | Sep 8 | Sep 23 |
| 32°F | Sep 6 | Sep 21 | Oct 4 |
| 28°F | Sep 17 | Sep 30 | Oct 15 |
| 24°F | Sep 29 | Oct 11 | Oct 25 |
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 | 77 days | 94 days | 112 days |
| 32°F | 105 days | 123 days | 141 days |
| 28°F | 128 days | 148 days | 169 days |
| 24°F | 154 days | 175 days | 194 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 |
|---|---|---|---|
| 99672 | 4b | -25 to -20°F | 12 km |
| 99568 | 5a | -20 to -15°F | 30 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 USC00508731, at 60.4906, -150.9189, elevation 89 m (292 ft).
- Data quality: Estimated from nearby stations (2+ years), 8 years of freeze data.
- Average days per year at or below 32°F: 200.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Soldotna 5ssw (14 km)
- Kenai Muni Airport (20 km)
- Kenai 9n (30 km)
- Kenai 29 ENE (36 km)
- Cooper Landing 5 W (52 km)
- Cooper Lake Project (70 km)
- Seward 8 NW (79 km)
- Moose Pass 3nw (82 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.