Frost dates for Mount Sunapee, NH
At Mount Sunapee, the median last spring frost (32°F) is May 2 and the median first fall frost is Oct 9, for a typical growing season of 158 days. For a 90% chance that the last frost has passed, wait until May 17. Nearby ZIP codes are in USDA hardiness zones 5b to 6a.
- May 2Last spring frost (median)50% chance of 32°F after this date
- May 17Safer planting date10% chance of 32°F after this date
- Oct 9First fall frost (median)50% chance of 32°F by this date
- 158 daysGrowing season (median)between 32°F freezes
USDA hardiness zone 5b (-15 to -10°F) · see all zone 5b frost dates
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 2 | May 14 | May 29 |
| 32°F | Apr 21 | May 2 | May 17 |
| 28°F | Apr 9 | Apr 21 | May 3 |
| 24°F | Mar 31 | Apr 10 | Apr 21 |
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 16 | Sep 30 | Oct 12 |
| 32°F | Sep 27 | Oct 9 | Oct 24 |
| 28°F | Oct 4 | Oct 21 | Nov 5 |
| 24°F | Oct 17 | Nov 3 | Nov 17 |
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 | 118 days | 137 days | 154 days |
| 32°F | 140 days | 158 days | 176 days |
| 28°F | 163 days | 181 days | 200 days |
| 24°F | 185 days | 204 days | 223 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 |
|---|---|---|---|
| 03255 | 5b | -15 to -10°F | 5 km |
| 03782 | 5b | -15 to -10°F | 7 km |
| 03752 | 6a | -10 to -5°F | 7 km |
| 03257 | 5b | -15 to -10°F | 12 km |
| 03260 | 5b | -15 to -10°F | 14 km |
| 03605 | 6a | -10 to -5°F | 14 km |
| 03233 | 5b | -15 to -10°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 USC00275629, at 43.3325, -72.0792, elevation 389 m (1,275 ft).
- Data quality: Representative (10+ years), 24 years of freeze data.
- Average days per year at or below 32°F: 152.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Newport (10 km)
- Bradford 2 (10 km)
- Salisbury (28 km)
- Grafton (28 km)
- Hopkinton Lake (31 km)
- Weare 2 NE (37 km)
- Lebanon Muni Airport (37 km)
- Franklin Falls Dam (38 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.