Frost dates for Norwich Public Utility Plant, CT
At Norwich Public Utility Plant, the median last spring frost (32°F) is Apr 14 and the median first fall frost is Oct 24, for a typical growing season of 192 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zone 6b.
- Apr 14Last spring frost (median)50% chance of 32°F after this date
- Apr 30Safer planting date10% chance of 32°F after this date
- Oct 24First fall frost (median)50% chance of 32°F by this date
- 192 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 16 | Apr 30 | May 13 |
| 32°F | Apr 1 | Apr 14 | Apr 30 |
| 28°F | Mar 18 | Apr 1 | Apr 16 |
| 24°F | Mar 6 | Mar 23 | Apr 3 |
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 | Oct 1 | Oct 12 | Oct 29 |
| 32°F | Oct 9 | Oct 24 | Nov 7 |
| 28°F | Oct 19 | Nov 5 | Nov 21 |
| 24°F | Nov 1 | Nov 18 | Dec 5 |
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 | 147 days | 166 days | 187 days |
| 32°F | 170 days | 192 days | 211 days |
| 28°F | 197 days | 216 days | 236 days |
| 24°F | 220 days | 242 days | 263 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 |
|---|---|---|---|
| 06360 | 6b | -5 to 0°F | 3 km |
| 06380 | 6b | -5 to 0°F | 4 km |
| 06365 | 6b | -5 to 0°F | 5 km |
| 06389 | 6b | -5 to 0°F | 6 km |
| 06382 | 6b | -5 to 0°F | 9 km |
| 06334 | 6b | -5 to 0°F | 9 km |
| 06338 | 6b | -5 to 0°F | 10 km |
| 06351 | 6b | -5 to 0°F | 12 km |
| 06330 | 6b | -5 to 0°F | 12 km |
| 06370 | 6b | -5 to 0°F | 12 km |
| 06254 | 6b | -5 to 0°F | 12 km |
| 06336 | 6b | -5 to 0°F | 12 km |
| 06420 | 6b | -5 to 0°F | 17 km |
| 06384 | 6b | -5 to 0°F | 20 km |
| 06415 | 6b | -5 to 0°F | 24 km |
| 06423 | 6b | -5 to 0°F | 28 km |
| 06439 | 6b | -5 to 0°F | 30 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 USC00065910, at 41.5267, -72.0653, elevation 6 m (20 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 124.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Groton (20 km)
- Groton New London Airport (22 km)
- Willimantic Windham Airport (26 km)
- Hampton (27 km)
- Storrs (33 km)
- W Thompson Lake (48 km)
- Hartford Brainard Field (54 km)
- Staffordville (55 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.