Frost dates for Rockville 1 NE, MD
At Rockville 1 NE, the median last spring frost (32°F) is Apr 1 and the median first fall frost is Nov 6, for a typical growing season of 219 days. For a 90% chance that the last frost has passed, wait until Apr 15. Nearby ZIP codes are in USDA hardiness zone 7b.
- Apr 1Last spring frost (median)50% chance of 32°F after this date
- Apr 15Safer planting date10% chance of 32°F after this date
- Nov 6First fall frost (median)50% chance of 32°F by this date
- 219 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 | Mar 31 | Apr 16 | May 5 |
| 32°F | Mar 19 | Apr 1 | Apr 15 |
| 28°F | Mar 5 | Mar 22 | Apr 4 |
| 24°F | Feb 23 | Mar 10 | Mar 25 |
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 12 | Oct 25 | Nov 7 |
| 32°F | Oct 24 | Nov 6 | Nov 21 |
| 28°F | Nov 5 | Nov 19 | Dec 6 |
| 24°F | Nov 14 | Dec 2 | Dec 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 | 170 days | 192 days | 212 days |
| 32°F | 200 days | 219 days | 240 days |
| 28°F | 224 days | 243 days | 267 days |
| 24°F | 244 days | 268 days | 294 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 |
|---|---|---|---|
| 20850 | 7b | 5 to 10°F | 3 km |
| 20851 | 7b | 5 to 10°F | 3 km |
| 20855 | 7b | 5 to 10°F | 4 km |
| 20853 | 7b | 5 to 10°F | 5 km |
| 20880 | 7b | 5 to 10°F | 5 km |
| 20877 | 7b | 5 to 10°F | 6 km |
| 20852 | 7b | 5 to 10°F | 6 km |
| 20879 | 7b | 5 to 10°F | 8 km |
| 20899 | 7b | 5 to 10°F | 8 km |
| 20832 | 7b | 5 to 10°F | 8 km |
| 20906 | 7b | 5 to 10°F | 8 km |
| 20896 | 7b | 5 to 10°F | 9 km |
| 20878 | 7b | 5 to 10°F | 9 km |
| 20854 | 7b | 5 to 10°F | 10 km |
| 20895 | 7b | 5 to 10°F | 10 km |
| 20860 | 7b | 5 to 10°F | 11 km |
| 20874 | 7b | 5 to 10°F | 14 km |
| 20833 | 7b | 5 to 10°F | 14 km |
| 20862 | 7b | 5 to 10°F | 14 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 USC00187705, at 39.1008, -77.1486, elevation 134 m (440 ft).
- Data quality: Representative (10+ years), 14 years of freeze data.
- Average days per year at or below 32°F: 86.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Dalecarlia Rsvr (18 km)
- Damascus 3 SSW (20 km)
- Beltsville (20 km)
- Laurel 3 W (22 km)
- National Arboretum DC (26 km)
- Glenn Dale Bell Station (33 km)
- Oxon Hill (36 km)
- Baltimore Wash Intl Airport (41 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.