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 50312
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 50312 in zone 5b (the coldest night of a typical year: -15 to -10°F).
The nearest station, Des Moines, IA, is 3 miles from the ZIP's center: its last spring frost comes after April 18 in half of years and after May 2 in one year in ten. By the USDA's method its plant hardiness zone is 5b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Des Moines, IADes Moines International Airport | 3 mi | 957 ft | April 18 | May 2 | October 20 | 5b |
| Ankeny, IA | 11 mi | 975 ft | April 23 | May 6 | October 15 | 5b |
| Des Moines Weather Office-Johnston, IA | 11 mi | 959 ft | April 19 | May 3 | October 18 | 5b |
| Indianola, IA2 mi W | 15 mi | 924 ft | April 24 | May 8 | October 12 | 5b |
| Des Moines (17 mi E), IA | 21 mi | 921 ft | April 21 | May 5 | October 15 | – |
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 Des Moines
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 3 | April 29 | April 15 | October 9 | September 25 |
| 32°F | May 2 | April 24 | April 18 | April 4 | October 20 | October 4 |
| 28°F (hard freeze) | April 22 | April 13 | April 8 | March 25 | October 30 | October 16 |
| 24°F | April 13 | April 5 | March 31 | March 12 | November 6 | October 25 |
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.