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 46324
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 46324 in zone 6a (the coldest night of a typical year: -10 to -5°F).
The nearest station, Park Forest, IL, is 11 miles from the ZIP's center: its last spring frost comes after April 23 in half of years and after May 11 in one year in ten. By the USDA's method its plant hardiness zone is 6a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Park Forest, IL | 11 mi | 710 ft | April 23 | May 11 | October 20 | 6a |
| Burbank, ILChicago Midway Airport (3 mi SW) | 18 mi | 620 ft | April 10 | April 26 | November 1 | – |
| Chicago Midway Airport, IL | 19 mi | 612 ft | April 11 | April 27 | October 31 | 6a |
| Chicago Northerly Island, IL | 20 mi | 583 ft | April 10 | April 25 | November 5 | – |
| Little Red School House, IL | 21 mi | 715 ft | April 19 | May 5 | October 22 | – |
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 Park Forest
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 24 | May 13 | May 5 | April 20 | October 10 | September 27 |
| 32°F | May 11 | April 30 | April 23 | April 9 | October 20 | October 6 |
| 28°F (hard freeze) | April 27 | April 19 | April 12 | March 30 | October 30 | October 18 |
| 24°F | April 17 | April 6 | April 1 | March 15 | November 11 | October 29 |
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.