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 59727
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 59727 in zone 5a (the coldest night of a typical year: -20 to -15°F).
The nearest station, Divide, MT, is 5 miles from the ZIP's center: its last spring frost comes after June 10 in half of years and after July 2 in one year in ten. By the USDA's method its plant hardiness zone is 4b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Divide, MT | 5 mi | 5,350 ft | June 10 | July 2 | September 7 | 4b |
| Butte, MTButte Bert Mooney Airport | 20 mi | 5,506 ft | June 13 | July 1 | September 5 | 4a |
| Anaconda, MT | 23 mi | 5,230 ft | June 1 | June 25 | September 14 | 5a |
| Twin Bridges, MT | 30 mi | 4,625 ft | June 8 | July 1 | September 2 | 5a |
| Dillon, MTDillon Airport | 40 mi | 5,200 ft | June 2 | June 21 | September 13 | – |
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 Divide
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% |
|---|---|---|---|---|---|---|
| 32°F | July 2 | June 18 | June 10 | May 23 | September 7 | August 24 |
| 28°F (hard freeze) | June 9 | May 28 | May 21 | May 6 | September 19 | September 3 |
| 24°F | May 21 | May 13 | May 7 | April 22 | October 1 | September 14 |
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.