Last spring frost
Mar 2
Frost Dates for Glen Ellen, CA
First fall frost
Nov 27
Growing season
270 days
Hardiness zone
9b
In an average year around Glen Ellen, CA, the last spring frost (32°F) is about Mar 2 and the first fall frost is about Nov 27, giving roughly a 270-day growing season. To be safe most years, wait until Jan 27 before setting out tender plants.
Last spring frost
Dates the last frost of spring typically ends. Plant tender crops after the risk has passed for your comfort level.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Apr 29 | Apr 8 | Mar 14 |
| Freeze (32°F) | Apr 5 | Mar 2 | Jan 27 |
| Hard (28°F) | Feb 22 | Jan 20 | Dec 20 |
| Severe (24°F) | Jan 29 | Jan 1 | Dec 10 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 29 | Apr 24 | Apr 18 | Apr 14 | Apr 8 | Apr 3 | Mar 30 | Mar 24 | Mar 14 |
| 32°F | Apr 5 | Mar 23 | Mar 13 | Mar 6 | Mar 2 | Feb 25 | Feb 17 | Feb 7 | Jan 27 |
| 28°F | Feb 22 | Feb 11 | Feb 1 | Jan 27 | Jan 20 | Jan 12 | Jan 4 | Dec 29 | Dec 20 |
| 24°F | Jan 29 | Jan 16 | Jan 10 | Jan 5 | Jan 1 | Dec 30 | Dec 23 | Dec 16 | Dec 10 |
First fall frost
Dates the first frost of fall typically arrives. Count back by a crop's days-to-maturity to know your planting cutoff.
| Frost intensity | Early (10%) | Average (50%) | Late (90%) |
|---|---|---|---|
| Light (36°F) | Oct 25 | Nov 8 | Nov 26 |
| Freeze (32°F) | Nov 6 | Nov 27 | Dec 21 |
| Hard (28°F) | Nov 24 | Dec 14 | Jan 17 |
| Severe (24°F) | Dec 3 | Dec 28 | Jan 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 25 | Oct 30 | Nov 1 | Nov 4 | Nov 8 | Nov 10 | Nov 14 | Nov 19 | Nov 26 |
| 32°F | Nov 6 | Nov 12 | Nov 18 | Nov 23 | Nov 27 | Dec 1 | Dec 4 | Dec 10 | Dec 21 |
| 28°F | Nov 24 | Dec 1 | Dec 5 | Dec 9 | Dec 14 | Dec 19 | Dec 27 | Jan 4 | Jan 17 |
| 24°F | Dec 3 | Dec 10 | Dec 15 | Dec 21 | Dec 28 | Dec 31 | Jan 4 | Jan 10 | Jan 23 |
Growing season is measured at 32°F with about 50% probability. Hardiness zone from the 2023 USDA map; frost normals from NOAA 1991-2020.
Where this data comes from
@endif These dates are computed from the nearest official weather station with long-term records: Sonoma, Ca, about 6.2 miles away@if(!empty($station['elevation_ft'])), at 97 ft elevation. The further the station and the greater the elevation difference from your yard, the more your local frost timing can vary.
How we calculate these dates
Frost and freeze dates come from the NOAA 1991–2020 U.S. Climate Normals, the National Oceanic and Atmospheric Administration's 30-year averages for each weather station. A date shown at the 50% level is the median: in half of years the frost falls on or before it. The 10% and 90% columns show the early and late ends of the range, so you can plant on the odds you're comfortable with. These are long-term averages, not a forecast for this year - always check your local outlook before planting.
Source: NOAA National Centers for Environmental Information, 1991–2020 Climate Normals (public domain). Harman is not affiliated with or endorsed by NOAA.
Frequently asked questions
When is the last frost in Glen Ellen, CA?
On average, the last spring frost (32°F) around Glen Ellen, CA is about Mar 2. In cooler years it can run later, so for a safer bet many gardeners wait until Jan 27.
When is the first frost in the fall?
The first fall frost around Glen Ellen, CA typically arrives about Nov 27. Count back by a crop's days to maturity to find the latest date you can plant it.
When can I plant tomatoes and other tender crops?
Tender crops like tomatoes, peppers and basil are damaged by frost, so wait until the last spring frost has passed - around Mar 2 on average, or Jan 27 to be safe most years.
How long is the growing season here?
The frost-free growing season (between the last spring and first fall 32°F frost) is about 270 days in a typical year.
Are these dates a forecast for this year?
No. They are 30-year averages from the NOAA 1991–2020 Climate Normals, not a prediction for the current year. Use them for planning and always check your local weather forecast before planting or protecting crops.
Local weather for 95442 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026