Last spring frost
Apr 23
Frost Dates for Castella, CA
First fall frost
Oct 27
Growing season
185 days
Hardiness zone
8a
In an average year around Castella, CA, the last spring frost (32°F) is about Apr 23 and the first fall frost is about Oct 27, giving roughly a 185-day growing season. To be safe most years, wait until Apr 5 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) | Jun 3 | May 11 | Apr 27 |
| Freeze (32°F) | May 12 | Apr 23 | Apr 5 |
| Hard (28°F) | Apr 21 | Mar 31 | Mar 1 |
| Severe (24°F) | Mar 28 | Feb 20 | Jan 11 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 3 | May 28 | May 20 | May 15 | May 11 | May 8 | May 5 | May 1 | Apr 27 |
| 32°F | May 12 | May 5 | May 1 | Apr 27 | Apr 23 | Apr 20 | Apr 17 | Apr 12 | Apr 5 |
| 28°F | Apr 21 | Apr 16 | Apr 10 | Apr 5 | Mar 31 | Mar 27 | Mar 21 | Mar 12 | Mar 1 |
| 24°F | Mar 28 | Mar 11 | Mar 3 | Feb 27 | Feb 20 | Feb 14 | Feb 4 | Jan 27 | Jan 11 |
| 20°F | Feb 23 | Feb 11 | Feb 2 | Jan 25 | Jan 15 | Jan 8 | Jan 1 | Dec 23 | Dec 12 |
| 16°F | Jan 26 | Jan 17 | Jan 9 | Jan 3 | Dec 31 | Dec 25 | Dec 20 | Dec 15 | Dec 9 |
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) | Sep 23 | Oct 9 | Oct 24 |
| Freeze (32°F) | Oct 9 | Oct 27 | Nov 10 |
| Hard (28°F) | Oct 28 | Nov 12 | Dec 2 |
| Severe (24°F) | Nov 11 | Dec 3 | Jan 3 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 23 | Sep 28 | Oct 1 | Oct 5 | Oct 9 | Oct 13 | Oct 16 | Oct 20 | Oct 24 |
| 32°F | Oct 9 | Oct 16 | Oct 20 | Oct 24 | Oct 27 | Oct 30 | Nov 1 | Nov 5 | Nov 10 |
| 28°F | Oct 28 | Nov 2 | Nov 6 | Nov 9 | Nov 12 | Nov 16 | Nov 21 | Nov 26 | Dec 2 |
| 24°F | Nov 11 | Nov 18 | Nov 24 | Nov 30 | Dec 3 | Dec 7 | Dec 13 | Dec 20 | Jan 3 |
| 20°F | Nov 28 | Dec 4 | Dec 10 | Dec 15 | Dec 21 | Dec 29 | Jan 4 | Jan 16 | Jan 31 |
| 16°F | Dec 7 | Dec 12 | Dec 17 | Dec 20 | Dec 25 | Dec 31 | Jan 6 | Jan 15 | Jan 21 |
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: Dunsmuir Trtmt Pl, Ca, about 2.3 miles away@if(!empty($station['elevation_ft'])), at 2,169 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 Castella, CA?
On average, the last spring frost (32°F) around Castella, CA is about Apr 23. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 5.
When is the first frost in the fall?
The first fall frost around Castella, CA typically arrives about Oct 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 Apr 23 on average, or Apr 5 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 185 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 96025 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026