Frost dates for Whittier, AK
At Whittier, the median last spring frost (32°F) is Apr 25 and the median first fall frost is Oct 14, for a typical growing season of 172 days. For a 90% chance that the last frost has passed, wait until May 8. Nearby ZIP codes are in USDA hardiness zones 5a to 7a.
- Apr 25Last spring frost (median)50% chance of 32°F after this date
- May 8Safer planting date10% chance of 32°F after this date
- Oct 14First fall frost (median)50% chance of 32°F by this date
- 172 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 | Apr 30 | May 11 | May 23 |
| 32°F | Apr 12 | Apr 25 | May 8 |
| 28°F | Mar 30 | Apr 11 | Apr 25 |
| 24°F | Mar 12 | Apr 1 | Apr 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 |
|---|---|---|---|
| 36°F | Sep 19 | Oct 1 | Oct 16 |
| 32°F | Oct 1 | Oct 14 | Oct 30 |
| 28°F | Oct 10 | Oct 26 | Nov 11 |
| 24°F | Oct 20 | Nov 7 | Nov 24 |
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 | 125 days | 143 days | 162 days |
| 32°F | 152 days | 172 days | 193 days |
| 28°F | 176 days | 198 days | 219 days |
| 24°F | 197 days | 220 days | 243 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 |
|---|---|---|---|
| 99587 | 5b | -15 to -10°F | 23 km |
| 99693 | 7a | 0 to 5°F | 36 km |
| 99540 | 5b | -15 to -10°F | 43 km |
| 99605 | 5b | -15 to -10°F | 44 km |
| 99577 | 5a | -20 to -15°F | 55 km |
| 99631 | 5a | -20 to -15°F | 56 km |
| 99567 | 5a | -20 to -15°F | 61 km |
| 99507 | 5a | -20 to -15°F | 63 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 USC00509829, at 60.7764, -148.6858, elevation 18 m (60 ft).
- Data quality: Representative (10+ years), 16 years of freeze data.
- Average days per year at or below 32°F: 127.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Portage Glacier V C (8 km)
- Alyeska (31 km)
- Wally Noerenberg Hatchery (33 km)
- Main Bay (43 km)
- Moose Pass 3nw (51 km)
- Hope (53 km)
- Seward 19n (59 km)
- Eagle River Nature Center (60 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.