Frost dates for 95370Sonora, CA
The average last spring frost in Sonora is April 9 and the average first fall frost is November 9, giving a typical growing season of about 213 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 9
- Average first fall frost
- Nov 9
- Growing season
- 213 days
Safer after Apr 30 (1-in-10 risk)
Possible by Oct 19 (1-in-10 risk)
First frost typically in 10 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 11 · Apr 30 · May 19 | Oct 7 · Oct 25 · Nov 12 | 178 days | 100% |
| Frost / freeze (32°F) | Mar 15 · Apr 9 · Apr 30 | Oct 19 · Nov 9 · Nov 27 | 213 days | 100% |
| Hard freeze (28°F) | Jan 31 · Mar 4 · Apr 8 | Nov 7 · Nov 27 · Dec 19 | 264 days | 100% |
Planting calendar for Sonora
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 9 – May 15 |
| Tomatoes | Transplant outdoors | Apr 25 – Jul 20 |
| Peppers | Start seeds indoors | Mar 9 – Apr 9 |
| Peppers | Transplant outdoors | May 9 – Jun 9 |
| Eggplant | Start seeds indoors | Mar 26 – Apr 24 |
| Eggplant | Transplant outdoors | May 9 – Jun 9 |
| Cucumbers | Sow outdoors | May 9 – Jul 30 |
| Summer squash | Sow outdoors | Apr 25 – Jun 9 |
| Winter squash & pumpkins | Sow outdoors | May 9 – Jun 9 |
| Snap beans | Sow outdoors | Apr 25 – Aug 22 |
| Sweet corn | Sow outdoors | Apr 25 – Jul 20 |
| Watermelon & cantaloupe | Sow outdoors | May 9 – Jun 9 |
| Okra | Sow outdoors | May 2 – May 25 |
| Peas | Sow outdoors (spring) | Mar 9 – Apr 24 |
| Potatoes | Plant outdoors (spring) | Mar 9 – May 9 |
| Onions | Start seeds indoors (spring) | Jan 26 – Feb 22 |
| Onions | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (spring) | Feb 19 – Mar 25 |
| Broccoli | Transplant outdoors (spring) | Mar 26 – Apr 24 |
| Broccoli | Start seeds indoors (fall) | Jul 10 – Jul 20 |
| Broccoli | Transplant outdoors (fall) | Aug 9 – Aug 20 |
| Cabbage | Start seeds indoors (spring) | Feb 9 – Mar 9 |
| Cabbage | Transplant outdoors (spring) | Mar 9 – Apr 9 |
| Cabbage | Start seeds indoors (fall) | Jun 30 – Jul 30 |
| Cabbage | Transplant outdoors (fall) | Jul 30 – Aug 30 |
| Leaf lettuce | Sow outdoors (spring) | Mar 9 – May 25 |
| Leaf lettuce | Sow outdoors (fall) | Jul 30 – Sep 15 |
| Spinach | Sow outdoors (spring) | Mar 2 – Apr 15 |
| Spinach | Sow outdoors (fall) | Aug 16 – Sep 20 |
| Radishes | Sow outdoors (spring) | Mar 9 – Apr 29 |
| Radishes | Sow outdoors (fall) | Jul 30 – Sep 30 |
| Kale | Sow outdoors (spring) | Mar 26 – Apr 15 |
| Kale | Sow outdoors (fall) | Jul 23 – Aug 30 |
| Carrots | Sow outdoors (spring) | Apr 9 – May 25 |
| Carrots | Sow outdoors (fall) | Jun 30 – Aug 15 |
| Garlic | Plant outdoors (fall) | Oct 30 – Nov 30 |
Where these dates come from
ZIP code 95370 is matched to the NOAA station Sonora, CA, 5.4 km away, at 1,675 ft elevation (851 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Sonora, CA (used) | 1,675 ft | Apr 9 | Nov 9 |
| New Melones Dam Hq, CA | 960 ft | Feb 20 | Dec 11 |
| Groveland 2, CA | 2,800 ft | Apr 22 | Nov 2 |
| Calaveras Big Trees, CA | 4,695 ft | May 7 | Oct 28 |
Frost dates near Sonora
- Standard, CA 95373 · last Apr 9, first Nov 9
- Soulsbyville, CA 95372 · last Apr 22, first Nov 2
- Columbia, CA 95310 · last Apr 9, first Nov 9
- Tuolumne, CA 95379 · last Apr 22, first Nov 2
- Twain Harte, CA 95383 · last Apr 16, first Nov 12
- Mi Wuk Village, CA 95346 · last May 7, first Oct 28
- Chinese Camp, CA 95309 · last Feb 20, first Dec 11
- Vallecito, CA 95251 · last Apr 9, first Nov 9
Frequently asked questions
- When is the last frost in Sonora, CA?
- For ZIP code 95370, the average last spring frost (32°F) is April 9, based on NOAA 1991-2020 climate normals for the Sonora, CA weather station. There is a 1-in-10 chance of a frost after April 30.
- When is the first frost in Sonora, CA?
- The average first fall frost (32°F) is November 9. There is a 1-in-10 chance of frost by October 19, so tender plants are at risk from that point on.
- How long is the growing season in 95370?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 213 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.