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 94533
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 94533 in zone 9b (the coldest night of a typical year: 25 to 30°F).
The nearest station, Fairfield, CA, is 3 miles from the ZIP's center: its last spring frost comes after January 15 in half of years and after February 16 in one year in ten. By the USDA's method its plant hardiness zone is 9b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Fairfield, CA | 3 mi | 40 ft | January 15 | February 16 | December 14 | 9b |
| Vacaville, CAVacaville Nut Tree Airport | 7 mi | 109 ft | February 18 | March 25 | November 28 | 9b |
| Vacaville station, CA | 8 mi | 110 ft | January 31 | March 11 | December 11 | – |
| Napa State Hospital, CA | 14 mi | 35 ft | February 12 | March 13 | December 4 | 9b |
| Lake Solano, CA | 15 mi | 187 ft | February 4 | March 9 | December 5 | 9b |
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 Fairfield
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 11 | February 25 | January 23 | December 1 | November 13 |
| 32°F | February 16 | January 28 | January 15 | December 22 | December 14 | November 29 |
| 28°F (hard freeze) | January 19 | January 6 | December 31 | December 13 | December 24 | December 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.