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 94040
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 94040 in zone 9b (the coldest night of a typical year: 25 to 30°F).
The nearest station, Sunnyvale, CA, is 3 miles from the ZIP's center: its last spring frost comes after January 6 in half of years and after February 4 in one year in ten. By the USDA's method its plant hardiness zone is 10a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Sunnyvale, CAMoffett Federal Airfield | 3 mi | 39 ft | January 6 | February 4 | December 23 | 10a |
| Palo Alto, CA | 5 mi | 25 ft | February 1 | March 4 | December 7 | – |
| Skyline Ridge Preserve, CA | 7 mi | 2,270 ft | March 21 | April 28 | December 15 | – |
| San Jose, CA | 9 mi | 51 ft | January 12 | February 14 | December 22 | 10a |
| Newark, CA | 10 mi | 10 ft | January 1 | January 22 | December 27 | 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 Sunnyvale
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 6 | February 19 | February 6 | January 3 | December 6 | November 20 |
| 32°F | February 4 | January 18 | January 6 | December 16 | December 23 | December 3 |
| 28°F (hard freeze) | January 22 | January 8 | January 1 | December 16 | December 31 | 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.