Frost dates for Washington DC Dulles Airport, VA
At Washington DC Dulles Airport, the median last spring frost (32°F) is Apr 15 and the median first fall frost is Oct 24, for a typical growing season of 194 days. For a 90% chance that the last frost has passed, wait until Apr 30. Nearby ZIP codes are in USDA hardiness zones 7a to 7b.
- Apr 15Last 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
- 194 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 12 | Apr 29 | May 17 |
| 32°F | Mar 31 | Apr 15 | Apr 30 |
| 28°F | Mar 18 | Apr 1 | Apr 16 |
| 24°F | Mar 3 | Mar 20 | 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 2 | Oct 14 | Oct 27 |
| 32°F | Oct 10 | Oct 24 | Nov 5 |
| 28°F | Oct 21 | Nov 4 | Nov 19 |
| 24°F | Nov 3 | Nov 17 | 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 | 148 days | 170 days | 189 days |
| 32°F | 170 days | 194 days | 214 days |
| 28°F | 197 days | 218 days | 240 days |
| 24°F | 223 days | 243 days | 267 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 |
|---|---|---|---|
| 20151 | 7b | 5 to 10°F | 5 km |
| 20171 | 7b | 5 to 10°F | 6 km |
| 20152 | 7a | 0 to 5°F | 7 km |
| 20170 | 7b | 5 to 10°F | 8 km |
| 20120 | 7a | 0 to 5°F | 9 km |
| 20143 | 7a | 0 to 5°F | 11 km |
| 20169 | 7a | 0 to 5°F | 17 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 USW00093738, at 38.9408, -77.4636, elevation 88 m (290 ft).
- Data quality: Standard (24+ years of data), 26 years of freeze data.
- Average days per year at or below 32°F: 102.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- WFO Sterling (4 km)
- Vienna (16 km)
- Manassas (23 km)
- Purcellville (31 km)
- Washington Reagan Airport (39 km)
- Warrenton 3 SE (39 km)
- Mount Wx (39 km)
- Mount Wx 3 (40 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.