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 58203
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 58203 in zone 4a (the coldest night of a typical year: -30 to -25°F).
The nearest station, Grand Forks, ND, is 2 miles from the ZIP's center: its last spring frost comes after May 16 in half of years and after May 31 in one year in ten. By the USDA's method its plant hardiness zone is 4a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Grand Forks, NDGrand Forks International Airport | 2 mi | 842 ft | May 16 | May 31 | September 27 | 4a |
| Grand Forks University (NWS), ND | 5 mi | 830 ft | May 10 | May 24 | October 1 | 4a |
| Warren, MNWarren Wsd | 24 mi | 855 ft | May 5 | May 22 | October 2 | – |
| Larimore, ND4 mi SW | 26 mi | 1,152 ft | May 11 | May 25 | September 28 | – |
| Crookston, MNCrookston NW Experiment Station | 28 mi | 891 ft | May 11 | May 25 | September 27 | 3b |
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 Grand Forks
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 7 | June 1 | May 26 | May 13 | September 18 | September 4 |
| 32°F | May 31 | May 21 | May 16 | May 3 | September 27 | September 15 |
| 28°F (hard freeze) | May 19 | May 10 | May 4 | April 20 | October 5 | September 23 |
| 24°F | May 9 | April 30 | April 24 | April 7 | October 15 | 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.