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 15203
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 15203 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, West Mifflin, PA, is 6 miles from the ZIP's center: its last spring frost comes after April 18 in half of years and after May 6 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 |
|---|---|---|---|---|---|---|
| West Mifflin, PAPittsburgh Allegheny County Airport | 6 mi | 1,248 ft | April 18 | May 6 | October 28 | 7a |
| Braddock, PABraddock Lock 2 | 7 mi | 730 ft | April 5 | April 22 | November 10 | – |
| Emsworth, PAEmsworth L/D Ohio River | 8 mi | 717 ft | April 24 | May 11 | October 27 | – |
| McKeesport, PA | 9 mi | 740 ft | May 2 | May 20 | October 20 | 6b |
| Acmetonia Lock 3, PA | 11 mi | 748 ft | April 16 | May 4 | 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 West Mifflin
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 16 | October 17 | October 4 |
| 32°F | May 6 | April 24 | April 18 | April 2 | October 28 | October 14 |
| 28°F (hard freeze) | April 21 | April 12 | April 5 | March 23 | November 8 | October 28 |
| 24°F | April 8 | April 1 | March 28 | March 12 | November 18 | 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.