Frost dates for Wilmington New Castle Co Airport, DE
At Wilmington New Castle Co Airport, the median last spring frost (32°F) is Apr 7 and the median first fall frost is Nov 1, for a typical growing season of 209 days. For a 90% chance that the last frost has passed, wait until Apr 21. Nearby ZIP codes are in USDA hardiness zone 7b.
- Apr 7Last spring frost (median)50% chance of 32°F after this date
- Apr 21Safer planting date10% chance of 32°F after this date
- Nov 1First fall frost (median)50% chance of 32°F by this date
- 209 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 7 | Apr 21 | May 7 |
| 32°F | Mar 26 | Apr 7 | Apr 21 |
| 28°F | Mar 11 | Mar 27 | Apr 9 |
| 24°F | Feb 27 | Mar 15 | Mar 29 |
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 8 | Oct 22 | Nov 3 |
| 32°F | Oct 19 | Nov 1 | Nov 15 |
| 28°F | Nov 1 | Nov 14 | Dec 1 |
| 24°F | Nov 11 | Nov 28 | Dec 16 |
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 | 162 days | 183 days | 205 days |
| 32°F | 186 days | 209 days | 228 days |
| 28°F | 214 days | 234 days | 255 days |
| 24°F | 236 days | 258 days | 281 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 |
|---|---|---|---|
| 19720 | 7b | 5 to 10°F | 3 km |
| 19804 | 7b | 5 to 10°F | 5 km |
| 08023 | 7b | 5 to 10°F | 9 km |
| 19808 | 7b | 5 to 10°F | 9 km |
| 08070 | 7b | 5 to 10°F | 9 km |
| 19706 | 7b | 5 to 10°F | 11 km |
| 19731 | 7b | 5 to 10°F | 18 km |
| 19730 | 7b | 5 to 10°F | 25 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 USW00013781, at 39.6728, -75.6008, elevation 24 m (79 ft).
- Data quality: Standard (24+ years of data), 30 years of freeze data.
- Average days per year at or below 32°F: 92.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Wilmington Porter Rsch (12 km)
- Newark Ag Farm (12 km)
- Dover (59 km)
- Greenwood 2ne (95 km)
- Lewes (106 km)
- Georgetown Sussex Co Airport (111 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.