Frost dates for Portland Intl Jetport, ME
At Portland Intl Jetport, the median last spring frost (32°F) is Apr 26 and the median first fall frost is Oct 15, for a typical growing season of 170 days. For a 90% chance that the last frost has passed, wait until May 7. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- Apr 26Last spring frost (median)50% chance of 32°F after this date
- May 7Safer planting date10% chance of 32°F after this date
- Oct 15First fall frost (median)50% chance of 32°F by this date
- 170 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 28 | May 7 | May 20 |
| 32°F | Apr 16 | Apr 26 | May 7 |
| 28°F | Apr 3 | Apr 14 | Apr 25 |
| 24°F | Mar 21 | Apr 3 | 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 24 | Oct 4 | Oct 17 |
| 32°F | Oct 2 | Oct 15 | Oct 30 |
| 28°F | Oct 14 | Oct 27 | Nov 9 |
| 24°F | Oct 26 | Nov 8 | Nov 23 |
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 | 132 days | 149 days | 164 days |
| 32°F | 153 days | 170 days | 188 days |
| 28°F | 177 days | 195 days | 212 days |
| 24°F | 202 days | 220 days | 239 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 |
|---|---|---|---|
| 04102 | 6a | -10 to -5°F | 1 km |
| 04106 | 6a | -10 to -5°F | 2 km |
| 04101 | 6a | -10 to -5°F | 4 km |
| 04103 | 6a | -10 to -5°F | 5 km |
| 04109 | 6a | -10 to -5°F | 6 km |
| 04092 | 5b | -15 to -10°F | 8 km |
| 04074 | 6a | -10 to -5°F | 9 km |
| 04107 | 6a | -10 to -5°F | 9 km |
| 04108 | 6a | -10 to -5°F | 9 km |
| 04105 | 6a | -10 to -5°F | 10 km |
| 04050 | 6a | -10 to -5°F | 13 km |
| 04110 | 6a | -10 to -5°F | 14 km |
| 04064 | 6a | -10 to -5°F | 16 km |
| 04019 | 6a | -10 to -5°F | 16 km |
| 04072 | 5b | -15 to -10°F | 17 km |
| 04017 | 6a | -10 to -5°F | 20 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 USW00014764, at 43.6497, -70.3003, elevation 14 m (45 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 144.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- West Buxton 2 NNW (25 km)
- Windham 2nw (27 km)
- Gray (27 km)
- Hollis (30 km)
- Kennebunkport (35 km)
- Poland (40 km)
- Brunswick NAS (41 km)
- Durham (42 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.