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 59105
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 59105 in zone 5a (the coldest night of a typical year: -20 to -15°F).
The nearest station, Billings, MT, is 6 miles from the ZIP's center: its last spring frost comes after May 4 in half of years and after May 18 in one year in ten. By the USDA's method its plant hardiness zone is 5a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Billings, MTBillings International Airport | 6 mi | 3,581 ft | May 4 | May 18 | October 7 | 5a |
| Billings Water Treatment Plant, MT | 8 mi | 3,097 ft | May 10 | May 24 | October 1 | 5a |
| Billings Weather Office, MT | 10 mi | 3,185 ft | May 5 | May 21 | October 3 | 5a |
| Huntley, MTHuntley Experiment Station | 12 mi | 3,034 ft | May 12 | May 26 | September 25 | 4a |
| Pompeys Pillar (15 mi N), MT | 32 mi | 3,390 ft | May 22 | June 7 | September 22 | 4a |
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 Billings
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 29 | May 21 | May 15 | May 2 | September 28 | September 16 |
| 32°F | May 18 | May 10 | May 4 | April 20 | October 7 | September 26 |
| 28°F (hard freeze) | May 7 | April 29 | April 21 | April 4 | October 16 | October 1 |
| 24°F | April 27 | April 15 | April 7 | March 20 | October 26 | October 8 |
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.