Frost dates for Harmony, ME
At Harmony, the median last spring frost (32°F) is May 11 and the median first fall frost is Oct 1, for a typical growing season of 141 days. For a 90% chance that the last frost has passed, wait until May 25. Nearby ZIP codes are in USDA hardiness zone 5a.
- May 11Last spring frost (median)50% chance of 32°F after this date
- May 25Safer planting date10% chance of 32°F after this date
- Oct 1First fall frost (median)50% chance of 32°F by this date
- 141 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 | May 9 | May 24 | Jun 5 |
| 32°F | Apr 30 | May 11 | May 25 |
| 28°F | Apr 20 | Apr 30 | May 12 |
| 24°F | Apr 7 | Apr 19 | Apr 30 |
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 8 | Sep 20 | Oct 3 |
| 32°F | Sep 18 | Oct 1 | Oct 13 |
| 28°F | Sep 29 | Oct 11 | Oct 28 |
| 24°F | Oct 9 | Oct 25 | Nov 9 |
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 | 102 days | 119 days | 136 days |
| 32°F | 122 days | 141 days | 159 days |
| 28°F | 146 days | 164 days | 183 days |
| 24°F | 170 days | 189 days | 207 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 |
|---|---|---|---|
| 04943 | 5a | -20 to -15°F | 8 km |
| 04912 | 5a | -20 to -15°F | 10 km |
| 04942 | 5a | -20 to -15°F | 11 km |
| 04971 | 5a | -20 to -15°F | 12 km |
| 04923 | 5a | -20 to -15°F | 13 km |
| 04924 | 5a | -20 to -15°F | 18 km |
| 04967 | 5a | -20 to -15°F | 22 km |
| 04920 | 5a | -20 to -15°F | 27 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 USC00173567, at 44.9467, -69.5456, elevation 98 m (320 ft).
- Data quality: Estimated from nearby stations (2+ years), 10 years of freeze data.
- Average days per year at or below 32°F: 178.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Corinna (24 km)
- E Sangerville (30 km)
- Madison (32 km)
- Dover-Foxcroft Wastewater Plant (39 km)
- Sebec Lake (42 km)
- Waterville Trtmt Plant (47 km)
- Barnard (49 km)
- New Sharon (50 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.