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 20603
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 20603 in zone 7b (the coldest night of a typical year: 5 to 10°F).
The nearest station, Oxon Hill, MD, is 12 miles from the ZIP's center: its last spring frost comes after April 3 in half of years and after April 15 in one year in ten. By the USDA's method its plant hardiness zone is 8a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Oxon Hill, MD | 12 mi | 190 ft | April 3 | April 15 | November 8 | 8a |
| Washington, DCWashington Reagan Airport | 15 mi | 10 ft | March 24 | April 6 | November 18 | 8a |
| Mechanicsville, MD5 mi NE | 16 mi | 100 ft | April 17 | May 2 | October 27 | 7b |
| Upper Marlboro, MD3 mi NNW | 19 mi | 130 ft | April 9 | April 24 | October 29 | 7b |
| National Arboretum DC, MD | 20 mi | 50 ft | March 29 | April 11 | November 8 | 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 Oxon Hill
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 | April 1 | October 27 | October 14 |
| 32°F | April 15 | April 7 | April 3 | March 19 | November 8 | October 24 |
| 28°F (hard freeze) | April 3 | March 28 | March 21 | March 5 | November 19 | November 5 |
| 24°F | March 26 | March 17 | March 11 | February 21 | 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.