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 53545
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 53545 in zone 5b (the coldest night of a typical year: -15 to -10°F).
The nearest station, Afton - Janesville Wastewater Treatment Plant, WI, is 7 miles from the ZIP's center: its last spring frost comes after April 26 in half of years and after May 11 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 |
|---|---|---|---|---|---|---|
| Afton - Janesville Wastewater Treatment Plant, WI | 7 mi | 762 ft | April 26 | May 11 | October 15 | 5b |
| Fort Atkinson, WI | 15 mi | 800 ft | April 28 | May 17 | October 13 | 5a |
| Stoughton, WI | 15 mi | 840 ft | April 30 | May 15 | October 11 | 5b |
| Clinton, WIClinton Wastewater Treatment Plant | 16 mi | 924 ft | April 30 | May 17 | October 10 | 5a |
| Beloit, WI | 16 mi | 788 ft | May 1 | May 16 | October 12 | 5b |
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 Afton - Janesville Wastewater Treatment Plant
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 23 | May 13 | May 6 | April 22 | October 4 | September 22 |
| 32°F | May 11 | May 1 | April 26 | April 13 | October 15 | October 1 |
| 28°F (hard freeze) | April 29 | April 21 | April 15 | April 2 | October 26 | October 12 |
| 24°F | April 17 | April 8 | April 3 | March 18 | November 5 | October 24 |
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.