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 80640
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 80640 in zone 5b (the coldest night of a typical year: -15 to -10°F).
The nearest station, Brighton, CO, is 5 miles from the ZIP's center: its last spring frost comes after May 3 in half of years and after May 16 in one year in ten. By the USDA's method its plant hardiness zone is 5b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Brighton, CO3 mi SE | 5 mi | 5,016 ft | May 3 | May 16 | October 7 | 5b |
| Northglenn, CO | 7 mi | 5,407 ft | May 2 | May 14 | October 11 | 6a |
| Denver-Stapleton, CO | 9 mi | 5,286 ft | May 4 | May 16 | October 8 | 6a |
| Denver, CODenver International Airport | 12 mi | 5,414 ft | May 5 | May 19 | October 9 | 5b |
| Denver Water Dept, CO | 13 mi | 5,228 ft | April 30 | May 13 | October 12 | 6b |
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 Brighton
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 27 | May 18 | May 13 | May 3 | September 30 | September 17 |
| 32°F | May 16 | May 8 | May 3 | April 22 | October 7 | September 26 |
| 28°F (hard freeze) | May 7 | April 30 | April 23 | April 8 | October 16 | October 4 |
| 24°F | April 28 | April 17 | April 9 | March 24 | October 26 | October 13 |
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.