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 85131
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 85131 in zone 9a (the coldest night of a typical year: 20 to 25°F).
The nearest station, Arizona City, AZ, is 9 miles from the ZIP's center: its last spring frost comes after February 28 in half of years and after March 14 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Arizona City, AZ | 9 mi | 1,525 ft | February 28 | March 14 | November 21 | – |
| Eloy, AZ4 mi NE | 9 mi | 1,545 ft | February 24 | March 18 | November 28 | – |
| Picacho, AZ8 mi SE | 10 mi | 1,981 ft | February 6 | March 5 | December 9 | 9b |
| Robson Ranch, AZ | 11 mi | 1,495 ft | February 7 | March 4 | December 3 | – |
| Casa Grande, AZ | 18 mi | 1,400 ft | February 5 | February 28 | December 6 | – |
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 Arizona City
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) | April 4 | March 25 | March 17 | February 27 | November 12 | October 25 |
| 32°F | March 14 | March 5 | February 28 | February 3 | November 21 | November 5 |
| 28°F (hard freeze) | March 1 | February 17 | February 6 | January 10 | December 4 | November 16 |
| 24°F | February 14 | January 31 | January 16 | December 19 | December 18 | November 27 |
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.