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 55906
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 55906 in zone 4b (the coldest night of a typical year: -25 to -20°F).
The nearest station, Byron, MN, is 12 miles from the ZIP's center: its last spring frost comes after May 12 in half of years and after May 25 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Byron, MNByron 4NORTH | 12 mi | 1,041 ft | May 12 | May 25 | September 28 | – |
| Rochester, MNRochester International Airport | 14 mi | 1,304 ft | April 30 | May 13 | October 6 | 5a |
| Theilman (1 mi SSW), MN | 16 mi | 753 ft | May 7 | May 22 | October 2 | 4a |
| Zumbrota, MN | 19 mi | 970 ft | May 9 | May 22 | September 30 | 4b |
| Grand Meadow, MN | 28 mi | 1,350 ft | May 6 | May 18 | October 1 | 4b |
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 Byron
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) | June 4 | May 28 | May 22 | May 8 | September 19 | September 5 |
| 32°F | May 25 | May 18 | May 12 | April 29 | September 28 | September 14 |
| 28°F (hard freeze) | May 15 | May 7 | May 2 | April 18 | October 5 | September 22 |
| 24°F | May 6 | April 28 | April 22 | April 6 | October 14 | October 2 |
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.