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 48640
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 48640 in zone 6a (the coldest night of a typical year: -10 to -5°F).
The nearest station, Midland, MI, is 7 miles from the ZIP's center: its last spring frost comes after April 29 in half of years and after May 16 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 |
|---|---|---|---|---|---|---|
| Midland, MI | 7 mi | 640 ft | April 29 | May 16 | October 16 | 6a |
| Oil City (2 mi S), MI | 13 mi | 680 ft | May 15 | June 2 | September 29 | – |
| Saginaw, MISaginaw Mbs International Airport | 13 mi | 660 ft | April 26 | May 13 | October 17 | 6a |
| Auburn, MI2 mi NE | 16 mi | 605 ft | May 3 | May 23 | October 14 | – |
| Alma, MI | 21 mi | 729 ft | May 1 | May 19 | October 13 | 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 Midland
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 28 | May 18 | May 10 | April 26 | October 4 | September 21 |
| 32°F | May 16 | May 5 | April 29 | April 16 | October 16 | October 1 |
| 28°F (hard freeze) | May 2 | April 23 | April 18 | April 4 | October 31 | October 15 |
| 24°F | April 20 | April 13 | April 6 | March 24 | November 12 | October 30 |
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.