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 80104
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 80104 in zone 5b (the coldest night of a typical year: -15 to -10°F).
The nearest station, Castle Rock, CO, is 9 miles from the ZIP's center: its last spring frost comes after May 9 in half of years and after May 24 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 |
|---|---|---|---|---|---|---|
| Castle Rock, CO | 9 mi | 6,185 ft | May 9 | May 24 | October 2 | 5b |
| Elizabeth, CO2 mi NW | 12 mi | 6,611 ft | May 16 | June 1 | October 2 | – |
| Monument station, CO | 14 mi | 7,080 ft | May 14 | May 31 | October 1 | – |
| Parker, CO | 15 mi | 5,904 ft | May 9 | May 23 | October 3 | – |
| Roxborough State Park, CO | 16 mi | 6,117 ft | May 16 | June 1 | October 1 | – |
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 Castle Rock
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 6 | May 28 | May 21 | May 9 | September 25 | September 11 |
| 32°F | May 24 | May 15 | May 9 | April 30 | October 2 | September 17 |
| 28°F (hard freeze) | May 14 | May 6 | May 1 | April 17 | October 12 | September 26 |
| 24°F | May 8 | April 28 | April 21 | April 4 | October 21 | October 6 |
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.