Frost dates for Plymouth, NH
At Plymouth, the median last spring frost (32°F) is May 20 and the median first fall frost is Sep 27, for a typical growing season of 128 days. For a 90% chance that the last frost has passed, wait until Jun 4. Nearby ZIP codes are in USDA hardiness zones 5a to 5b.
- May 20Last spring frost (median)50% chance of 32°F after this date
- Jun 4Safer planting date10% chance of 32°F after this date
- Sep 27First fall frost (median)50% chance of 32°F by this date
- 128 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 17 | May 31 | Jun 13 |
| 32°F | May 6 | May 20 | Jun 4 |
| 28°F | Apr 22 | May 7 | May 24 |
| 24°F | Apr 7 | Apr 23 | May 9 |
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 1 | Sep 15 | Sep 28 |
| 32°F | Sep 14 | Sep 27 | Oct 7 |
| 28°F | Sep 24 | Oct 6 | Oct 22 |
| 24°F | Oct 3 | Oct 19 | Nov 6 |
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 | 89 days | 107 days | 124 days |
| 32°F | 110 days | 128 days | 147 days |
| 28°F | 129 days | 151 days | 173 days |
| 24°F | 155 days | 178 days | 201 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 |
|---|---|---|---|
| 03245 | 5b | -15 to -10°F | 6 km |
| 03217 | 5b | -15 to -10°F | 6 km |
| 03264 | 5b | -15 to -10°F | 7 km |
| 03223 | 5a | -20 to -15°F | 9 km |
| 03241 | 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 USC00276945, at 43.7833, -71.6500, elevation 201 m (660 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 196.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Meredith 3 NNE (17 km)
- Waterville Valley Nepp (21 km)
- Wentworth (23 km)
- E Sandwich (25 km)
- Lincoln Nepp (29 km)
- Lakeport 2 (30 km)
- Tamworth 4 (32 km)
- Grafton (34 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.