Last spring frost
Apr 7
Frost Dates for Angwin, CA
First fall frost
Dec 5
Growing season
245 days
Hardiness zone
9b
In an average year around Angwin, CA, the last spring frost (32°F) is about Apr 7 and the first fall frost is about Dec 5, giving roughly a 245-day growing season. To be safe most years, wait until Feb 23 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) | May 25 | Apr 30 | Apr 6 |
| Freeze (32°F) | Apr 30 | Apr 7 | Feb 23 |
| Hard (28°F) | Apr 9 | Feb 18 | Dec 23 |
| Severe (24°F) | Feb 26 | Jan 1 | Dec 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 25 | May 15 | May 9 | May 4 | Apr 30 | Apr 26 | Apr 21 | Apr 16 | Apr 6 |
| 32°F | Apr 30 | Apr 23 | Apr 18 | Apr 13 | Apr 7 | Mar 31 | Mar 21 | Mar 9 | Feb 23 |
| 28°F | Apr 9 | Mar 30 | Mar 15 | Mar 2 | Feb 18 | Feb 3 | Jan 19 | Jan 4 | Dec 23 |
| 24°F | Feb 26 | Feb 8 | Jan 26 | Jan 13 | Jan 1 | Dec 27 | Dec 19 | Dec 10 | Dec 5 |
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 22 | Nov 15 | Dec 5 |
| Freeze (32°F) | Nov 14 | Dec 5 | Jan 1 |
| Hard (28°F) | Nov 29 | Dec 30 | Mar 4 |
| Severe (24°F) | Dec 4 | Dec 31 | Feb 24 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Oct 22 | Nov 1 | Nov 5 | Nov 10 | Nov 15 | Nov 18 | Nov 23 | Nov 30 | Dec 5 |
| 32°F | Nov 14 | Nov 21 | Nov 27 | Dec 1 | Dec 5 | Dec 9 | Dec 14 | Dec 21 | Jan 1 |
| 28°F | Nov 29 | Dec 6 | Dec 13 | Dec 20 | Dec 30 | Jan 4 | Jan 21 | Feb 4 | Mar 4 |
| 24°F | Dec 4 | Dec 10 | Dec 17 | Dec 23 | Dec 31 | Jan 6 | Jan 21 | Feb 2 | Feb 24 |
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: Angwin Pacific Union College, Ca, about 0.9 miles away@if(!empty($station['elevation_ft'])), at 1,715 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 Angwin, CA?
On average, the last spring frost (32°F) around Angwin, CA is about Apr 7. In cooler years it can run later, so for a safer bet many gardeners wait until Feb 23.
When is the first frost in the fall?
The first fall frost around Angwin, CA typically arrives about Dec 5. 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 Apr 7 on average, or Feb 23 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 245 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 94508 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026