Last spring frost
Feb 20
Frost Dates for Copperopolis, CA
First fall frost
Dec 11
Growing season
290 days
Hardiness zone
9b
In an average year around Copperopolis, CA, the last spring frost (32°F) is about Feb 20 and the first fall frost is about Dec 11, giving roughly a 290-day growing season. To be safe most years, wait until Jan 10 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 5 | Apr 7 | Mar 1 |
| Freeze (32°F) | Apr 7 | Feb 20 | Jan 10 |
| Hard (28°F) | Feb 15 | Jan 6 | Dec 16 |
| Severe (24°F) | Jan 15 | Dec 25 | Dec 12 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 5 | Apr 22 | Apr 16 | Apr 11 | Apr 7 | Apr 1 | Mar 24 | Mar 12 | Mar 1 |
| 32°F | Apr 7 | Mar 22 | Mar 7 | Feb 28 | Feb 20 | Feb 14 | Feb 6 | Jan 25 | Jan 10 |
| 28°F | Feb 15 | Feb 5 | Jan 26 | Jan 13 | Jan 6 | Dec 31 | Dec 29 | Dec 23 | Dec 16 |
| 24°F | Jan 15 | Dec 31 | Dec 30 | Dec 28 | Dec 25 | Dec 21 | Dec 18 | Dec 16 | Dec 12 |
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) | Nov 3 | Nov 24 | Dec 12 |
| Freeze (32°F) | Nov 24 | Dec 11 | Jan 8 |
| Hard (28°F) | Dec 5 | Dec 24 | Feb 1 |
| Severe (24°F) | Dec 10 | Dec 25 | Jan 5 |
Show full probability table (all thresholds & percentiles)
| °F | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Nov 3 | Nov 12 | Nov 17 | Nov 21 | Nov 24 | Nov 28 | Dec 2 | Dec 6 | Dec 12 |
| 32°F | Nov 24 | Nov 30 | Dec 4 | Dec 7 | Dec 11 | Dec 15 | Dec 20 | Dec 28 | Jan 8 |
| 28°F | Dec 5 | Dec 12 | Dec 17 | Dec 20 | Dec 24 | Dec 28 | Jan 2 | Jan 11 | Feb 1 |
| 24°F | Dec 10 | Dec 15 | Dec 18 | Dec 20 | Dec 25 | Dec 27 | Dec 29 | Dec 31 | Jan 5 |
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: New Melones Dam Hq, Ca, about 12.9 miles away@if(!empty($station['elevation_ft'])), at 960 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 Copperopolis, CA?
On average, the last spring frost (32°F) around Copperopolis, CA is about Feb 20. In cooler years it can run later, so for a safer bet many gardeners wait until Jan 10.
When is the first frost in the fall?
The first fall frost around Copperopolis, CA typically arrives about Dec 11. 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 Feb 20 on average, or Jan 10 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 290 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 95228 Planting calendar → California frost dates →
Data source: NOAA 1991–2020 Climate Normals · Page updated Aug 4, 2026