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 20194
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 20194 in zone 7b (the coldest night of a typical year: 5 to 10°F).
The nearest station, Vienna, VA, is 7 miles from the ZIP's center: its last spring frost comes after April 14 in half of years and after April 28 in one year in ten. By the USDA's method its plant hardiness zone is 7b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Vienna, VA | 7 mi | 418 ft | April 14 | April 28 | October 29 | 7b |
| Sterling, VAWashington Dulles International Airport | 7 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 |
| Dalecarlia Reservoir, MD | 13 mi | 150 ft | April 9 | April 26 | October 31 | 7b |
| Rockville, MD1 mi NE | 13 mi | 440 ft | April 1 | April 15 | November 6 | 7b |
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 Vienna
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 | May 1 | April 25 | April 11 | October 19 | October 7 |
| 32°F | April 28 | April 20 | April 14 | March 30 | October 29 | October 17 |
| 28°F (hard freeze) | April 16 | April 7 | April 2 | March 18 | November 8 | October 26 |
| 24°F | April 5 | March 29 | March 22 | March 4 | November 20 | November 5 |
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.