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 83702
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 83702 in zone 7a (the coldest night of a typical year: 0 to 5°F).
The nearest station, Boise (7 mi N), ID, is 6 miles from the ZIP's center: its last spring frost comes after May 17 in half of years and after June 10 in one year in ten. By the USDA's method its plant hardiness zone is 7a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Boise (7 mi N), ID | 6 mi | 3,885 ft | May 17 | June 10 | October 12 | 7a |
| Boise, IDBoise Air Terminal | 8 mi | 2,814 ft | April 24 | May 9 | October 21 | 7b |
| Boise Lucky Peak Dam, ID | 11 mi | 2,840 ft | April 30 | May 18 | October 22 | – |
| Arrowrock Dam, ID | 12 mi | 3,235 ft | April 28 | May 16 | October 14 | – |
| Idaho City, ID | 20 mi | 3,965 ft | June 17 | July 4 | September 5 | – |
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 Boise (7 mi N)
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 23 | June 13 | June 6 | May 18 | September 29 | September 13 |
| 32°F | June 10 | May 28 | May 17 | April 27 | October 12 | September 27 |
| 28°F (hard freeze) | May 19 | May 5 | April 27 | April 7 | October 24 | October 8 |
| 24°F | April 29 | April 13 | April 4 | March 7 | November 5 | October 19 |
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.