Frost dates for Ketchikan Intl Airport, AK
At Ketchikan Intl Airport, the median last spring frost (32°F) is Apr 22 and the median first fall frost is Oct 23, for a typical growing season of 185 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zones 7b to 8a.
- Apr 22Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 23First fall frost (median)50% chance of 32°F by this date
- 185 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 24 | May 8 | May 25 |
| 32°F | Apr 2 | Apr 22 | May 9 |
| 28°F | Mar 10 | Mar 31 | Apr 18 |
| 24°F | Feb 11 | Mar 12 | Mar 31 |
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 25 | Oct 6 | Oct 23 |
| 32°F | Oct 3 | Oct 23 | Nov 10 |
| 28°F | Oct 20 | Nov 10 | Dec 6 |
| 24°F | Nov 5 | Nov 29 | Dec 31 |
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 | 129 days | 151 days | 170 days |
| 32°F | 160 days | 185 days | 210 days |
| 28°F | 195 days | 225 days | 259 days |
| 24°F | 230 days | 262 days | 300 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 |
|---|---|---|---|
| 99926 | 8a | 10 to 15°F | 29 km |
| 99901 | 7b | 5 to 10°F | 40 km |
| 99903 | 7b | 5 to 10°F | 49 km |
| 99919 | 7b | 5 to 10°F | 59 km |
| 99921 | 7b | 5 to 10°F | 65 km |
| 99925 | 7b | 5 to 10°F | 81 km |
| 99922 | 8a | 10 to 15°F | 85 km |
| 99918 | 8a | 10 to 15°F | 88 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 USW00025325, at 55.3567, -131.7117, elevation 23 m (76 ft).
- Data quality: Standard (24+ years of data), 27 years of freeze data.
- Average days per year at or below 32°F: 82.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Beaver Falls (1 km)
- Ketchikan 10n (13 km)
- Metlakatla 6 S (35 km)
- Annette Island Airport (36 km)
- Thorne Bay (63 km)
- Klawock Airport (89 km)
- Craig (91 km)
- Hyder (123 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.