Frost dates for Santa Rosa
The typical last spring frost in Santa Rosa is Mar 2, and the typical first fall frost is Nov 20. These dates come from Santa Rosa Sonoma County Airport, and the growing season between them is 262 days.
NCEI U.S. Climate Normals 1991-2020, annual/seasonal (c20230404), USW00023213
This season's measured frost
No freeze has been recorded yet this fall at Santa Rosa Sonoma County Airport; the lowest reading since July 1 is 41F on Oct 11, against a typical first frost date of Nov 20.
In 2026, the last spring freeze at Santa Rosa Sonoma County Airport was on Feb 21 with a low of 32F, 9 days earlier than the typical date of Mar 2.
Readings come from official daily lows in the daily climate report of the National Weather Service, via the Iowa Environmental Mesonet.
Early, typical and late years for Santa Rosa
| Year type | Last spring frost | First fall frost |
|---|---|---|
| Early year (1 in 10) | Jan 27 | Nov 1 |
| Typical year | Mar 2 | Nov 20 |
| Late year (1 in 10) | Apr 2 | Dec 10 |
For spring, an early year means 1 year in 10 has a last freeze before the early date, and a late year means 1 year in 10 has a last freeze after the late date. For fall, an early year means 1 year in 10 has a first freeze by the early date, and a late year means it holds off past the late date.
The growing season in a typical year is 262 days, with the shortest at 223 days and the longest at 307 days in 1 year in 10.
Frost and freeze thresholds
| Last spring frost | First fall frost | |
|---|---|---|
| Light frost (36F) | Apr 12 | Nov 3 |
| Freeze (32F) | Mar 2 | Nov 20 |
| Hard freeze (28F) | Jan 23 | Dec 5 |
Clear, calm nights can see frost on plants at a low of 36F. A low of 32F is a freeze, and most tender plants are killed at 28F, a hard freeze.
More weather for Santa Rosa
A typical date is the median: half of years have an earlier last spring frost, half a later one. An early year means 1 year in 10, and a late year means 1 year in 10. Dates come from the U.S. Climate Normals for 1991-2020, published by NOAA's National Centers for Environmental Information, using a daily low of 32F or below as a freeze.
The daily climate report is issued by the local National Weather Service forecast office and delivered to this page by the Iowa Environmental Mesonet of Iowa State University. Under 17 U.S.C. 105, no copyright attaches to the government-produced figures on this page, including reports, alerts, station observations, and normals, which were created by the National Weather Service and other NOAA offices. The notice that 17 U.S.C. 403 requires appears in this sentence. It does not imply endorsement by or affiliation with those agencies. See: Data sources and attribution.