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 20120
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 20120 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, Sterling, VA, is 6 miles from the ZIP's center: its last spring frost comes after April 15 in half of years and after April 30 in one year in ten. By the USDA's method its plant hardiness zone is 7a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Sterling, VAWashington Dulles International Airport | 6 mi | 290 ft | April 15 | April 30 | October 24 | 7a |
| Weather Office Sterling, VA | 8 mi | 288 ft | April 13 | May 1 | October 26 | 7a |
| Manassas, VA | 9 mi | 245 ft | April 12 | April 24 | October 27 | – |
| Vienna, VA | 11 mi | 418 ft | April 14 | April 28 | October 29 | 7b |
| Warrenton, VA3 mi SE | 20 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 Sterling
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 17 | May 6 | April 29 | April 12 | October 14 | October 2 |
| 32°F | April 30 | April 21 | April 15 | March 31 | October 24 | October 10 |
| 28°F (hard freeze) | April 16 | April 6 | April 1 | March 18 | November 4 | October 21 |
| 24°F | April 3 | March 28 | March 20 | March 3 | November 17 | November 3 |
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.