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 21009
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 21009 in zone 7b (the coldest night of a typical year: 5 to 10°F).
The nearest station, Aberdeen, MD, is 6 miles from the ZIP's center: its last spring frost comes after April 10 in half of years and after April 30 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Aberdeen, MDAberdeen Phillips Field | 6 mi | 57 ft | April 10 | April 30 | October 30 | – |
| Conowingo Dam, MD | 14 mi | 40 ft | April 3 | April 18 | November 6 | – |
| Cylburn, MD | 21 mi | 235 ft | April 2 | April 13 | November 7 | – |
| Chestertown, MD | 22 mi | 40 ft | April 3 | April 16 | November 5 | 7b |
| Maryland Science Center Baltimore, MD | 22 mi | 20 ft | March 24 | April 4 | November 21 | 8a |
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 Aberdeen
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 12 | May 3 | April 27 | April 9 | October 19 | October 5 |
| 32°F | April 30 | April 17 | April 10 | March 27 | October 30 | October 14 |
| 28°F (hard freeze) | April 12 | April 3 | March 29 | March 13 | November 10 | October 28 |
| 24°F | March 31 | March 24 | March 18 | February 28 | November 24 | November 6 |
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.