Frost dates for Danbury Muni Airport, CT
At Danbury Muni Airport, the median last spring frost (32°F) is May 1 and the median first fall frost is Oct 14, for a typical growing season of 166 days. For a 90% chance that the last frost has passed, wait until May 16. Nearby ZIP codes are in USDA hardiness zones 6b to 7a.
- May 1Last spring frost (median)50% chance of 32°F after this date
- May 16Safer planting date10% chance of 32°F after this date
- Oct 14First fall frost (median)50% chance of 32°F by this date
- 166 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 30 | May 12 | May 27 |
| 32°F | Apr 18 | May 1 | May 16 |
| 28°F | Apr 3 | Apr 18 | May 4 |
| 24°F | Mar 21 | Apr 3 | Apr 19 |
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 21 | Oct 2 | Oct 16 |
| 32°F | Oct 1 | Oct 14 | Oct 29 |
| 28°F | Oct 11 | Oct 27 | Nov 8 |
| 24°F | Oct 24 | Nov 6 | Nov 23 |
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 | 126 days | 143 days | 162 days |
| 32°F | 146 days | 166 days | 187 days |
| 28°F | 168 days | 191 days | 211 days |
| 24°F | 195 days | 216 days | 237 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 |
|---|---|---|---|
| 06810 | 6b | -5 to 0°F | 2 km |
| 06877 | 6b | -5 to 0°F | 6 km |
| 10560 | 6b | -5 to 0°F | 10 km |
| 06896 | 6b | -5 to 0°F | 11 km |
| 10597 | 6b | -5 to 0°F | 13 km |
| 10590 | 6b | -5 to 0°F | 14 km |
| 10518 | 6b | -5 to 0°F | 15 km |
| 06883 | 7a | 0 to 5°F | 19 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 USW00054734, at 41.3714, -73.4828, elevation 139 m (457 ft).
- Data quality: Representative (10+ years), 17 years of freeze data.
- Average days per year at or below 32°F: 134.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Danbury (6 km)
- Stamford 5 N (28 km)
- Ansonia 1 NE (33 km)
- Bridgeport Sikorsky Mem Airport (38 km)
- Mount Carmel (49 km)
- New Haven Tweed Airport (51 km)
- Meriden Markham Muni Airport (57 km)
- Falls Village (65 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.