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 63303
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 63303 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, St. Peters, MO, is 3 miles from the ZIP's center: its last spring frost comes after April 9 in half of years and after April 25 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 |
|---|---|---|---|---|---|---|
| St. Peters, MOSt Peters (2 mi SE) | 3 mi | 575 ft | April 9 | April 25 | October 26 | 7a |
| St Charles (7 mi SSW), MO | 4 mi | 450 ft | April 4 | April 21 | October 29 | 6b |
| St Charles Elm Point, MO | 5 mi | 472 ft | April 8 | April 24 | October 29 | 6b |
| Weldon Spring, MOWeldon Spring NWS | 8 mi | 610 ft | April 10 | April 26 | October 26 | 6b |
| St Louis Spirit of St. Louis Airport, MO | 8 mi | 462 ft | April 12 | April 27 | October 23 | 6b |
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 St. Peters
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 8 | April 30 | April 23 | April 7 | October 17 | October 4 |
| 32°F | April 25 | April 17 | April 9 | March 27 | October 26 | October 14 |
| 28°F (hard freeze) | April 14 | April 5 | March 31 | March 12 | November 5 | October 25 |
| 24°F | April 4 | March 28 | March 20 | March 3 | November 18 | 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.