Last spring frost
May 7
Frost Dates for Mountain Ranch, CA
First fall frost
Oct 28
Growing season
169 days
Hardiness zone
9a
In an average year around Mountain Ranch, CA, the last spring frost (32°F) is about May 7 and the first fall frost is about Oct 28, giving roughly a 169-day growing season. To be safe most years, wait until Apr 18 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 14 | May 30 | May 7 |
| Freeze (32°F) | May 31 | May 7 | Apr 18 |
| Hard (28°F) | May 12 | Apr 18 | Mar 28 |
| Severe (24°F) | Apr 20 | Mar 27 | Feb 19 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Jun 14 | Jun 8 | Jun 4 | Jun 1 | May 30 | May 25 | May 20 | May 14 | May 7 |
| 32°F | May 31 | May 25 | May 18 | May 13 | May 7 | May 2 | Apr 29 | Apr 24 | Apr 18 |
| 28°F | May 12 | May 2 | Apr 28 | Apr 22 | Apr 18 | Apr 14 | Apr 10 | Apr 5 | Mar 28 |
| 24°F | Apr 20 | Apr 13 | Apr 8 | Apr 2 | Mar 27 | Mar 19 | Mar 13 | Mar 4 | Feb 19 |
| 20°F | Mar 31 | Mar 16 | Mar 6 | Feb 28 | Feb 20 | Feb 13 | Feb 4 | Jan 23 | Jan 5 |
| 16°F | Feb 28 | Feb 19 | Feb 8 | Jan 31 | Jan 22 | Jan 13 | Jan 5 | Dec 27 | Dec 15 |
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 24 | Oct 11 | Nov 1 |
| Freeze (32°F) | Oct 5 | Oct 28 | Nov 16 |
| Hard (28°F) | Oct 23 | Nov 14 | Dec 5 |
| Severe (24°F) | Nov 6 | Dec 3 | Dec 23 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 24 | Sep 29 | Oct 3 | Oct 6 | Oct 11 | Oct 15 | Oct 19 | Oct 24 | Nov 1 |
| 32°F | Oct 5 | Oct 12 | Oct 18 | Oct 23 | Oct 28 | Nov 1 | Nov 5 | Nov 9 | Nov 16 |
| 28°F | Oct 23 | Nov 1 | Nov 5 | Nov 10 | Nov 14 | Nov 19 | Nov 23 | Nov 29 | Dec 5 |
| 24°F | Nov 6 | Nov 16 | Nov 23 | Nov 28 | Dec 3 | Dec 6 | Dec 11 | Dec 16 | Dec 23 |
| 20°F | Nov 24 | Dec 3 | Dec 9 | Dec 16 | Dec 21 | Dec 27 | Jan 2 | Jan 17 | Feb 1 |
| 16°F | Dec 4 | Dec 14 | Dec 22 | Dec 29 | Jan 3 | Jan 12 | Jan 21 | Feb 1 | Feb 12 |
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: Calaveras Big Trees, Ca, about 9.8 miles away@if(!empty($station['elevation_ft'])), at 4,695 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 Mountain Ranch, CA?
On average, the last spring frost (32°F) around Mountain Ranch, CA is about May 7. In cooler years it can run later, so for a safer bet many gardeners wait until Apr 18.
When is the first frost in the fall?
The first fall frost around Mountain Ranch, CA typically arrives about Oct 28. 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 May 7 on average, or Apr 18 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 169 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 95246 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026