Frost dates by ZIP code: The nearest NOAA stations to your ZIP, 1991-2020 normals
Enter a five-digit ZIP code. PlainClimate finds its center (Census Bureau 2024) and the five nearest NOAA stations with frost dates, and shows each station's last spring and first autumn 32°F dates with its distance and elevation.
Frost dates near ZIP 21701
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 21701 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, Frederick, MD, is 6 miles from the ZIP's center: its last spring frost comes after April 2 in half of years and after April 15 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Frederick, MDFrederick Police Barracks | 6 mi | 380 ft | April 2 | April 15 | November 6 | – |
| Damascus, MD3 mi SSW | 13 mi | 700 ft | April 14 | May 2 | October 29 | 7a |
| Catoctin Mountain Park, MD | 16 mi | 1,610 ft | April 14 | April 30 | October 30 | 7a |
| Emmitsburg, MD2 mi SE | 16 mi | 403 ft | April 22 | May 9 | October 20 | 7a |
| Smithsburg, MD2 mi NW | 20 mi | 670 ft | April 25 | May 11 | October 19 | – |
Frost comes later in spring at higher and colder stations and earlier in low, open ground: prefer a station at a similar elevation to yours. Hardiness zone in the table: the USDA's rule (the average of each year's coldest night, 1991-2020) applied to the station's own record.
Every frost threshold at Frederick
NOAA publishes the dates for several temperatures and odds. A 30% spring date means a 3-in-10 chance of a later frost (the convention almanacs use); 50% is the median; 10% the cautious date.
| Threshold | Spring, 10% | Spring, 30% | Spring, 50% | Spring, 90% | Autumn, 50% | Autumn, 10% |
|---|---|---|---|---|---|---|
| 36°F (light frost) | May 2 | April 21 | April 15 | March 31 | October 24 | October 9 |
| 32°F | April 15 | April 7 | April 2 | March 17 | November 6 | October 23 |
| 28°F (hard freeze) | April 4 | March 29 | March 21 | March 3 | November 21 | November 6 |
| 24°F | March 26 | March 16 | March 9 | February 20 | December 7 | November 14 |
Source: NOAA NCEI 1991-2020 annual normals; ZIP centers: Census Bureau 2024 Gazetteer; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. Autumn 10%: one year in ten has its first frost before this date.