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 95403
The USDA's 2023 Plant Hardiness Zone Map puts ZIP 95403 in zone 9a (the coldest night of a typical year: 20 to 25°F).
The nearest station, Santa Rosa, CA, is 3 miles from the ZIP's center: its last spring frost comes after March 2 in half of years and after April 2 in one year in ten. By the USDA's method its plant hardiness zone is 9a.
| Station | Distance | Elevation | Last frost (median) | 1 in 10 after | First frost (median) | Hardiness zone |
|---|---|---|---|---|---|---|
| Santa Rosa, CASanta Rosa Sonoma County Airport | 3 mi | 114 ft | March 2 | April 2 | November 20 | 9a |
| Santa Rosa station, CA | 4 mi | 166 ft | February 25 | March 29 | December 1 | 9b |
| Graton, CA | 8 mi | 200 ft | March 20 | April 19 | November 13 | 9a |
| Calistoga, CA | 10 mi | 400 ft | March 2 | April 18 | November 23 | 9a |
| Healdsburg, CA | 11 mi | 177 ft | February 15 | March 17 | December 2 | 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 Santa Rosa
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) | May 1 | April 22 | April 12 | March 17 | November 3 | October 16 |
| 32°F | April 2 | March 14 | March 2 | January 27 | November 20 | November 1 |
| 28°F (hard freeze) | February 23 | February 5 | January 23 | December 20 | December 5 | November 15 |
| 24°F | January 27 | January 10 | December 31 | December 6 | December 19 | November 29 |
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.