Frost dates for 94517Clayton, CA
The average last spring frost in Clayton is February 15 and the average first fall frost is December 2, giving a typical growing season of about 292 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 15
- Average first fall frost
- Dec 2
- Growing season
- 292 days
Safer after Mar 13 (1-in-10 risk)
Possible by Nov 16 (1-in-10 risk)
First frost typically in 32 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) | Feb 26 · Mar 25 · Apr 13 | Nov 4 · Nov 18 · Dec 2 | 238 days | 100% |
| Frost / freeze (32°F) | Jan 12 · Feb 15 · Mar 13 | Nov 16 · Dec 2 · Dec 28 | 292 days | 99% |
| Hard freeze (28°F) | Dec 19 · Jan 10 · Feb 10 | Nov 29 · Dec 18 · Jan 17 | 343 days | 76% |
Planting calendar for Clayton
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 | Jan 15 – Mar 23 |
| Tomatoes | Transplant outdoors | Mar 3 – Aug 12 |
| Peppers | Start seeds indoors | Jan 15 – Feb 15 |
| Peppers | Transplant outdoors | Mar 17 – Apr 17 |
| Eggplant | Start seeds indoors | Feb 1 – Mar 2 |
| Eggplant | Transplant outdoors | Mar 17 – Apr 17 |
| Cucumbers | Sow outdoors | Mar 17 – Aug 22 |
| Summer squash | Sow outdoors | Mar 3 – Apr 17 |
| Winter squash & pumpkins | Sow outdoors | Mar 17 – Apr 17 |
| Snap beans | Sow outdoors | Mar 3 – Sep 14 |
| Sweet corn | Sow outdoors | Mar 3 – Aug 12 |
| Watermelon & cantaloupe | Sow outdoors | Mar 17 – Apr 17 |
| Okra | Sow outdoors | Mar 10 – Apr 2 |
| Peas | Sow outdoors (spring) | Jan 15 – Mar 2 |
| Potatoes | Plant outdoors (spring) | Jan 15 – Mar 17 |
| Onions | Start seeds indoors (spring) | Dec 4 – Dec 31 |
| Onions | Transplant outdoors (spring) | Feb 1 – Mar 2 |
| Broccoli | Start seeds indoors (spring) | Dec 28 – Jan 31 |
| Broccoli | Transplant outdoors (spring) | Feb 1 – Mar 2 |
| Broccoli | Start seeds indoors (fall) | Aug 2 – Aug 12 |
| Broccoli | Transplant outdoors (fall) | Sep 1 – Sep 12 |
| Cabbage | Start seeds indoors (spring) | Dec 18 – Jan 15 |
| Cabbage | Transplant outdoors (spring) | Jan 15 – Feb 15 |
| Cabbage | Start seeds indoors (fall) | Jul 23 – Aug 22 |
| Cabbage | Transplant outdoors (fall) | Aug 22 – Sep 22 |
| Leaf lettuce | Sow outdoors (spring) | Jan 15 – Apr 2 |
| Leaf lettuce | Sow outdoors (fall) | Aug 22 – Oct 8 |
| Spinach | Sow outdoors (spring) | Jan 8 – Feb 21 |
| Spinach | Sow outdoors (fall) | Sep 8 – Oct 13 |
| Radishes | Sow outdoors (spring) | Jan 15 – Mar 7 |
| Radishes | Sow outdoors (fall) | Aug 22 – Oct 23 |
| Kale | Sow outdoors (spring) | Feb 1 – Feb 21 |
| Kale | Sow outdoors (fall) | Aug 15 – Sep 22 |
| Carrots | Sow outdoors (spring) | Feb 15 – Apr 2 |
| Carrots | Sow outdoors (fall) | Jul 23 – Sep 7 |
| Garlic | Plant outdoors (fall) | Nov 22 – Dec 23 |
Where these dates come from
ZIP code 94517 is matched to the NOAA station Livermore, CA, 26.1 km away, at 393 ft elevation (503 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Livermore, CA (used) | 393 ft | Feb 15 | Dec 2 |
| Mt Diablo Junction, CA | 2,170 ft | Mar 8 | Dec 22 |
| Concord Buchanan Fld, CA | 18 ft | Jan 9 | Dec 14 |
| Antioch Pumping Plt #3, CA | 60 ft | Jan 12 | Dec 19 |
Frost dates near Clayton
- Concord, CA 94527 · last Jan 7, first Dec 19
- Danville, CA 94506 · last Feb 27, first Dec 1
- Pittsburg, CA 94565 · last Jan 9, first Dec 14
- Diablo, CA 94528 · last Feb 27, first Dec 1
- Walnut Creek, CA 94598 · last Jan 7, first Dec 19
- Alamo, CA 94507 · last Jan 3, first Jan 1
- Antioch, CA 94509 · last Jan 12, first Dec 19
- Pleasant Hill, CA 94523 · last Jan 7, first Dec 19
Frequently asked questions
- When is the last frost in Clayton, CA?
- For ZIP code 94517, the average last spring frost (32°F) is February 15, based on NOAA 1991-2020 climate normals for the Livermore, CA weather station. There is a 1-in-10 chance of a frost after March 13.
- When is the first frost in Clayton, CA?
- The average first fall frost (32°F) is December 2. There is a 1-in-10 chance of frost by November 16, so tender plants are at risk from that point on.
- How long is the growing season in 94517?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 292 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.