Frost dates for McGrath Airport, AK
At McGrath Airport, the median last spring frost (32°F) is May 13 and the median first fall frost is Sep 13, for a typical growing season of 120 days. For a 90% chance that the last frost has passed, wait until May 28. Nearby ZIP codes are in USDA hardiness zones 2a to 3a.
- May 13Last spring frost (median)50% chance of 32°F after this date
- May 28Safer planting date10% chance of 32°F after this date
- Sep 13First fall frost (median)50% chance of 32°F by this date
- 120 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 14 | May 25 | Jun 7 |
| 32°F | May 4 | May 13 | May 28 |
| 28°F | Apr 25 | May 4 | May 18 |
| 24°F | Apr 16 | Apr 29 | May 9 |
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 14 | Aug 31 | Sep 15 |
| 32°F | Aug 27 | Sep 13 | Sep 27 |
| 28°F | Sep 7 | Sep 25 | Oct 7 |
| 24°F | Sep 19 | Oct 3 | Oct 16 |
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 | 73 days | 96 days | 116 days |
| 32°F | 99 days | 120 days | 139 days |
| 28°F | 121 days | 141 days | 159 days |
| 24°F | 138 days | 157 days | 175 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 |
|---|---|---|---|
| 99675 | 2a | -50 to -45°F | 22 km |
| 99627 | 2b | -45 to -40°F | 84 km |
| 99656 | 3a | -40 to -35°F | 151 km |
| 99668 | 2b | -45 to -40°F | 164 km |
| 99503 | 3a | -40 to -35°F | 166 km |
| 99575 | 3a | -40 to -35°F | 181 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 USW00026510, at 62.9575, -155.6103, elevation 102 m (333 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 221.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Farewell Lake (111 km)
- Puntilla (176 km)
- Ruby 44 ESE (186 km)
- Minchumina (196 km)
- Galena (208 km)
- Hayes River (211 km)
- Kaltag Airport (217 km)
- Denali 27 N (244 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.