Frost dates for Port Alcan, AK
At Port Alcan, the median last spring frost (32°F) is May 28 and the median first fall frost is Aug 29, for a typical growing season of 91 days. For a 90% chance that the last frost has passed, wait until Jun 10. Nearby ZIP codes are in USDA hardiness zones 1b to 4b.
- May 28Last spring frost (median)50% chance of 32°F after this date
- Jun 10Safer planting date10% chance of 32°F after this date
- Aug 29First fall frost (median)50% chance of 32°F by this date
- 91 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 15 | May 28 | Jun 10 |
| 28°F | May 5 | May 15 | May 30 |
| 24°F | Apr 26 | May 5 | May 18 |
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 14 | Aug 29 | Sep 8 |
| 28°F | Aug 30 | Sep 9 | Sep 20 |
| 24°F | Sep 8 | Sep 21 | Oct 1 |
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 | 42 days | 63 days | 82 days |
| 32°F | 74 days | 91 days | 108 days |
| 28°F | 97 days | 115 days | 131 days |
| 24°F | 120 days | 137 days | 151 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 100% |
Closest ZIP codes (each is closer to another station)
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99764 | 2a | -50 to -45°F | 42 km |
| 99780 | 2a | -50 to -45°F | 116 km |
| 99776 | 1b | -55 to -50°F | 148 km |
| 99586 | 2b | -45 to -40°F | 165 km |
| 99732 | 1b | -55 to -50°F | 169 km |
| 99566 | 4b | -25 to -20°F | 172 km |
| 99737 | 3a | -40 to -35°F | 235 km |
| 99706 | 3b | -35 to -30°F | 240 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 USC00507513, at 62.6211, -141.0061, elevation 577 m (1,892 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 246.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Tok 70 SE (17 km)
- Northway Airport (60 km)
- Nabesna (105 km)
- Tok #2 (127 km)
- Tok (130 km)
- McCarthy 3 SW (169 km)
- Chicken (170 km)
- Silver Lake (206 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.