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 61821
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 61821 in zone 6a (the coldest night of a typical year: -10 to -5°F).
The nearest station, Champaign (3 mi S), IL, is 3 miles from the ZIP's center: its last spring frost comes after April 15 in half of years and after April 29 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Champaign (3 mi S), IL | 3 mi | 721 ft | April 15 | April 29 | October 24 | – |
| Champaign, ILChampaign Willard Airport | 5 mi | 754 ft | April 19 | May 5 | October 17 | 6a |
| Champaign (9 mi SW), IL | 7 mi | 700 ft | April 23 | May 9 | October 13 | 5b |
| Rantoul, IL | 15 mi | 740 ft | April 21 | May 6 | October 18 | 6a |
| Ogden, IL | 17 mi | 675 ft | April 20 | May 7 | October 21 | 6a |
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 Champaign (3 mi S)
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 2 | April 26 | April 12 | October 15 | October 1 |
| 32°F | April 29 | April 21 | April 15 | April 1 | October 24 | October 11 |
| 28°F (hard freeze) | April 19 | April 10 | April 4 | March 20 | November 2 | October 22 |
| 24°F | April 9 | March 31 | March 25 | March 9 | November 12 | November 1 |
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.