Frost dates for Westport Island, ME
At Westport Island, the median last spring frost (32°F) is Apr 28 and the median first fall frost is Oct 21, for a typical growing season of 175 days. For a 90% chance that the last frost has passed, wait until May 9. Nearby ZIP codes are in USDA hardiness zone 6a.
- Apr 28Last spring frost (median)50% chance of 32°F after this date
- May 9Safer planting date10% chance of 32°F after this date
- Oct 21First fall frost (median)50% chance of 32°F by this date
- 175 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 10 | May 23 |
| 32°F | Apr 16 | Apr 28 | May 9 |
| 28°F | Apr 3 | Apr 13 | Apr 26 |
| 24°F | Mar 21 | Apr 3 | Apr 15 |
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 7 | Oct 20 |
| 32°F | Oct 5 | Oct 21 | Nov 4 |
| 28°F | Oct 22 | Nov 4 | Nov 17 |
| 24°F | Nov 4 | Nov 17 | Nov 28 |
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 | 147 days | 165 days |
| 32°F | 156 days | 175 days | 195 days |
| 28°F | 186 days | 203 days | 221 days |
| 24°F | 210 days | 226 days | 244 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 |
|---|---|---|---|
| 04571 | 6a | -10 to -5°F | 3 km |
| 04575 | 6a | -10 to -5°F | 5 km |
| 04537 | 6a | -10 to -5°F | 7 km |
| 04548 | 6a | -10 to -5°F | 7 km |
| 04538 | 6a | -10 to -5°F | 8 km |
| 04576 | 6a | -10 to -5°F | 9 km |
| 04570 | 6a | -10 to -5°F | 11 km |
| 04544 | 6a | -10 to -5°F | 12 km |
| 04568 | 6a | -10 to -5°F | 12 km |
| 04558 | 6a | -10 to -5°F | 15 km |
| 04562 | 6a | -10 to -5°F | 16 km |
| 04554 | 6a | -10 to -5°F | 16 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 USC00179547, at 43.8881, -69.7089, elevation 27 m (90 ft).
- Data quality: Representative (10+ years), 11 years of freeze data.
- Average days per year at or below 32°F: 148.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Wiscasset Airport (8 km)
- Bath (13 km)
- Brunswick NAS (18 km)
- Newcastle (22 km)
- Durham (33 km)
- Gardiner (37 km)
- Tenants Harbor (41 km)
- Gray (44 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.