Frost dates for Danbury, CT
At Danbury, the median last spring frost (32°F) is Apr 20 and the median first fall frost is Oct 20, for a typical growing season of 181 days. For a 90% chance that the last frost has passed, wait until May 6. Nearby ZIP codes are in USDA hardiness zones 6a to 6b.
- Apr 20Last spring frost (median)50% chance of 32°F after this date
- May 6Safer planting date10% chance of 32°F after this date
- Oct 20First fall frost (median)50% chance of 32°F by this date
- 181 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 19 | May 3 | May 19 |
| 32°F | Apr 7 | Apr 20 | May 6 |
| 28°F | Mar 26 | Apr 7 | Apr 21 |
| 24°F | Mar 12 | Mar 29 | Apr 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 27 | Oct 9 | Oct 24 |
| 32°F | Oct 5 | Oct 20 | Nov 4 |
| 28°F | Oct 15 | Nov 1 | Nov 15 |
| 24°F | Oct 29 | Nov 14 | Dec 1 |
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 | 136 days | 156 days | 176 days |
| 32°F | 160 days | 181 days | 202 days |
| 28°F | 186 days | 206 days | 226 days |
| 24°F | 210 days | 229 days | 251 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 |
|---|---|---|---|
| 06801 | 6b | -5 to 0°F | 4 km |
| 06811 | 6b | -5 to 0°F | 5 km |
| 06804 | 6b | -5 to 0°F | 7 km |
| 06470 | 6b | -5 to 0°F | 9 km |
| 06812 | 6b | -5 to 0°F | 10 km |
| 06752 | 6b | -5 to 0°F | 14 km |
| 06488 | 6b | -5 to 0°F | 18 km |
| 06612 | 6b | -5 to 0°F | 18 km |
| 06783 | 6b | -5 to 0°F | 20 km |
| 06776 | 6b | -5 to 0°F | 22 km |
| 06798 | 6b | -5 to 0°F | 25 km |
| 06793 | 6a | -10 to -5°F | 28 km |
| 06794 | 6a | -10 to -5°F | 29 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 USC00061762, at 41.4003, -73.4211, elevation 123 m (405 ft).
- Data quality: Representative (10+ years), 25 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
- Danbury Muni Airport (6 km)
- Ansonia 1 NE (28 km)
- Stamford 5 N (32 km)
- Bridgeport Sikorsky Mem Airport (36 km)
- Mount Carmel (43 km)
- New Haven Tweed Airport (47 km)
- Meriden Markham Muni Airport (51 km)
- Burlington (60 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.