Frost dates for Frederick Police Brks, MD
At Frederick Police Brks, the median last spring frost (32°F) is Apr 2 and the median first fall frost is Nov 6, for a typical growing season of 218 days. For a 90% chance that the last frost has passed, wait until Apr 15. Nearby ZIP codes are in USDA hardiness zones 7a to 7b.
- Apr 2Last 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
- 218 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 15 | May 2 |
| 32°F | Mar 17 | Apr 2 | Apr 15 |
| 28°F | Mar 3 | Mar 21 | Apr 4 |
| 24°F | Feb 20 | Mar 9 | Mar 26 |
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 9 | Oct 24 | Nov 6 |
| 32°F | Oct 23 | Nov 6 | Nov 24 |
| 28°F | Nov 6 | Nov 21 | Dec 11 |
| 24°F | Nov 14 | Dec 7 | Dec 28 |
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 | 193 days | 213 days |
| 32°F | 196 days | 218 days | 239 days |
| 28°F | 223 days | 245 days | 271 days |
| 24°F | 246 days | 272 days | 298 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 |
|---|---|---|---|
| 21705 | 7b | 5 to 10°F | 3 km |
| 21714 | 7b | 5 to 10°F | 6 km |
| 21703 | 7b | 5 to 10°F | 6 km |
| 21702 | 7a | 0 to 5°F | 7 km |
| 21717 | 7b | 5 to 10°F | 9 km |
| 21704 | 7a | 0 to 5°F | 9 km |
| 21701 | 7a | 0 to 5°F | 10 km |
| 21793 | 7a | 0 to 5°F | 11 km |
| 21769 | 7a | 0 to 5°F | 12 km |
| 21710 | 7b | 5 to 10°F | 12 km |
| 21755 | 7b | 5 to 10°F | 13 km |
| 21774 | 7a | 0 to 5°F | 14 km |
| 21777 | 7a | 0 to 5°F | 17 km |
| 21762 | 7a | 0 to 5°F | 18 km |
| 21790 | 7a | 0 to 5°F | 18 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 USC00183348, at 39.4161, -77.4389, elevation 116 m (380 ft).
- Data quality: Representative (10+ years), 12 years of freeze data.
- Average days per year at or below 32°F: 84.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Sharpsburg 5 S (24 km)
- Damascus 3 SSW (25 km)
- Catoctin Mountain Park (26 km)
- Smithsburg 2nw (30 km)
- Emmitsburg 2 SE (32 km)
- Hagerstown 1 E (33 km)
- Hagerstown Washington Co Airport (41 km)
- Rockville 1 NE (43 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.