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 94401
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 94401 in zone 10a (the coldest night of a typical year: 30 to 35°F).
The nearest station, San Francisco International Airport, CA, is 4 miles from the ZIP's center: a night at 32°F or colder comes there in only 12% of years, and NOAA's median date of the last spring frost is December 29. By the USDA's method its plant hardiness zone is 10b.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| San Francisco International Airport, CA | 4 mi | 8 ft | December 29 | January 13 | December 26 | 10b |
| Redwood City, CA | 8 mi | 31 ft | January 17 | February 16 | December 12 | 9b |
| Pacifica, CA4 mi SSE | 8 mi | 475 ft | January 11 | February 12 | January 10 | – |
| Half Moon Bay, CA | 10 mi | 27 ft | February 6 | March 25 | December 17 | 10a |
| Woodside, CAWoodside Fire Station 1 | 11 mi | 380 ft | February 25 | April 11 | November 25 | – |
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 San Francisco International Airport
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) | February 14 | January 22 | January 8 | December 16 | December 24 | December 5 |
| 32°F | January 13 | January 3 | December 29 | December 11 | December 26 | December 11 |
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.