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 94590
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 94590 in zone 9b (the coldest night of a typical year: 25 to 30°F).
The nearest station, Vallejo, CA, is 3 miles from the ZIP's center: its last spring frost comes after January 17 in half of years and after March 4 in one year in ten.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Vallejo, CA | 3 mi | 341 ft | January 17 | March 4 | December 27 | – |
| Napa, CANapa County Airport | 8 mi | 14 ft | March 5 | April 16 | November 21 | 9a |
| Martinez, CAMartinez Water Treatment Plant | 9 mi | 40 ft | February 28 | April 5 | November 22 | 9b |
| Concord Wastewater Treatment Plant, CA | 13 mi | 40 ft | January 7 | February 1 | December 19 | 10a |
| Napa State Hospital, CA | 13 mi | 35 ft | February 12 | March 13 | December 4 | 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 Vallejo
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 8 | March 20 | March 4 | January 19 | December 7 | November 21 |
| 32°F | March 4 | February 2 | January 17 | December 23 | December 27 | December 4 |
| 28°F (hard freeze) | January 19 | January 11 | January 5 | December 19 | January 2 | December 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.