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 20121
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 20121 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, Manassas, VA, is 6 miles from the ZIP's center: its last spring frost comes after April 12 in half of years and after April 24 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Manassas, VA | 6 mi | 245 ft | April 12 | April 24 | October 27 | – |
| Sterling, VAWashington Dulles International Airport | 9 mi | 290 ft | April 15 | April 30 | October 24 | 7a |
| Vienna, VA | 11 mi | 418 ft | April 14 | April 28 | October 29 | 7b |
| Weather Office Sterling, VA | 11 mi | 288 ft | April 13 | May 1 | October 26 | 7a |
| Warrenton, VA3 mi SE | 19 mi | 500 ft | April 9 | April 28 | November 1 | – |
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 Manassas
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 10 | April 30 | April 24 | April 11 | October 18 | October 6 |
| 32°F | April 24 | April 17 | April 12 | March 30 | October 27 | October 13 |
| 28°F (hard freeze) | April 14 | April 6 | April 1 | March 17 | November 5 | October 24 |
| 24°F | April 4 | March 28 | March 20 | March 2 | November 16 | November 2 |
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.