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 48239
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 48239 in zone 6b (the coldest night of a typical year: -5 to 0°F).
The nearest station, Dearborn, MI, is 5 miles from the ZIP's center: its last spring frost comes after May 1 in half of years and after May 18 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 |
|---|---|---|---|---|---|---|
| Dearborn, MI | 5 mi | 605 ft | May 1 | May 18 | October 15 | 6a |
| Dearborn #2, MI | 6 mi | 605 ft | April 27 | May 11 | October 25 | – |
| Farmington, MI | 7 mi | 720 ft | May 1 | May 16 | October 17 | 6b |
| Detroit, MIDetroit Metro Airport | 10 mi | 631 ft | April 20 | May 8 | October 27 | 6b |
| Detroit City Airport, MI | 14 mi | 626 ft | April 21 | May 6 | October 31 | 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 Dearborn
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 27 | May 19 | May 12 | April 27 | October 5 | September 24 |
| 32°F | May 18 | May 8 | May 1 | April 17 | October 15 | October 1 |
| 28°F (hard freeze) | May 7 | April 26 | April 20 | April 5 | October 28 | October 13 |
| 24°F | April 21 | April 13 | April 6 | March 23 | November 10 | October 27 |
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.