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 21204
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 21204 in zone 7b (the coldest night of a typical year: 5 to 10°F).
The nearest station, Cylburn, MD, is 4 miles from the ZIP's center: its last spring frost comes after April 2 in half of years and after April 13 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Cylburn, MD | 4 mi | 235 ft | April 2 | April 13 | November 7 | – |
| Maryland Science Center Baltimore, MD | 9 mi | 20 ft | March 24 | April 4 | November 21 | 8a |
| Baltimore, MDBaltimore Wash International Airport | 17 mi | 156 ft | April 10 | April 25 | October 31 | 7b |
| Millers (4 mi NE), MD | 24 mi | 860 ft | April 19 | May 8 | October 25 | 7a |
| Aberdeen, MDAberdeen Phillips Field | 25 mi | 57 ft | April 10 | April 30 | October 30 | – |
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 Cylburn
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 1 | April 21 | April 14 | April 2 | October 27 | October 13 |
| 32°F | April 13 | April 6 | April 2 | March 20 | November 7 | October 27 |
| 28°F (hard freeze) | April 3 | March 29 | March 22 | March 8 | November 20 | November 6 |
| 24°F | March 26 | March 18 | March 13 | February 25 | December 5 | November 17 |
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.