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 94404
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 94404 in zone 10a (the coldest night of a typical year: 30 to 35°F).
The nearest station, Redwood City, CA, is 6 miles from the ZIP's center: its last spring frost comes after January 17 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 |
|---|---|---|---|---|---|---|
| Redwood City, CA | 6 mi | 31 ft | January 17 | February 16 | December 12 | 9b |
| San Francisco International Airport, CA | 7 mi | 8 ft | December 29 | January 13 | December 26 | 10b |
| Woodside, CAWoodside Fire Station 1 | 9 mi | 380 ft | February 25 | April 11 | November 25 | – |
| Palo Alto, CA | 10 mi | 25 ft | February 1 | March 4 | December 7 | – |
| Hayward, CAHayward Air Terminal | 11 mi | 43 ft | January 2 | January 27 | December 25 | 10a |
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 Redwood 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) | March 31 | March 7 | February 25 | January 25 | November 25 | November 8 |
| 32°F | February 16 | January 31 | January 17 | December 20 | December 12 | November 24 |
| 28°F (hard freeze) | January 22 | January 8 | December 31 | December 14 | December 26 | December 5 |
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.