Frost dates for Hartford Bradley Intl Airport, CT
At Hartford Bradley Intl Airport, the median last spring frost (32°F) is Apr 21 and the median first fall frost is Oct 16, for a typical growing season of 177 days. For a 90% chance that the last frost has passed, wait until May 6. Nearby ZIP codes are in USDA hardiness zone 6b.
- Apr 21Last spring frost (median)50% chance of 32°F after this date
- May 6Safer planting date10% chance of 32°F after this date
- Oct 16First fall frost (median)50% chance of 32°F by this date
- 177 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 22 | May 5 | May 18 |
| 32°F | Apr 8 | Apr 21 | May 6 |
| 28°F | Mar 26 | Apr 7 | Apr 22 |
| 24°F | Mar 14 | Mar 28 | Apr 7 |
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 26 | Oct 6 | Oct 21 |
| 32°F | Oct 3 | Oct 16 | Nov 2 |
| 28°F | Oct 13 | Oct 29 | Nov 12 |
| 24°F | Oct 27 | Nov 11 | Nov 26 |
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 | 135 days | 153 days | 172 days |
| 32°F | 157 days | 177 days | 198 days |
| 28°F | 184 days | 204 days | 223 days |
| 24°F | 208 days | 228 days | 250 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 |
|---|---|---|---|
| 06096 | 6b | -5 to 0°F | 3 km |
| 06080 | 6b | -5 to 0°F | 4 km |
| 06026 | 6b | -5 to 0°F | 5 km |
| 06078 | 6b | -5 to 0°F | 6 km |
| 06095 | 6b | -5 to 0°F | 7 km |
| 06081 | 6b | -5 to 0°F | 8 km |
| 06088 | 6b | -5 to 0°F | 9 km |
| 06093 | 6b | -5 to 0°F | 9 km |
| 06035 | 6b | -5 to 0°F | 10 km |
| 06002 | 6b | -5 to 0°F | 11 km |
| 06082 | 6b | -5 to 0°F | 12 km |
| 06016 | 6b | -5 to 0°F | 12 km |
| 06070 | 6b | -5 to 0°F | 13 km |
| 01106 | 6b | -5 to 0°F | 15 km |
| 06072 | 6b | -5 to 0°F | 17 km |
| 01028 | 6b | -5 to 0°F | 21 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 USW00014740, at 41.9381, -72.6825, elevation 58 m (190 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 126.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Hartford Brainard Field (23 km)
- Barkhamsted (23 km)
- Burlington (26 km)
- Bakersville (29 km)
- Staffordville (36 km)
- Storrs (41 km)
- Norfolk 2 SW (45 km)
- Willimantic Windham Airport (47 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.