Antioch, California: planting zone & frost dates
Antioch is in USDA plant hardiness zone 9b, where the average coldest winter night reaches 25 to 30°F (-3.9 to -1.1°C). The typical last spring frost is around Jan 22 and the first fall frost around Dec 10.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 1 | Nov 29 |
| Typical planning date (30% risk) | Jan 22 | Dec 10 |
| Median (50%) | Jan 12 | Dec 19 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station ANTIOCH PUMPING PLT #3, CA (USC00040232), 2.4 mi (3.9 km) from the city center and 157 ft lower than the city center (-48 m). Record used for the 1991–2020 normals: 19 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Antioch
All 3 ZIP codes covering Antioch are in zone 9b.
Vegetable planting calendar for Antioch
Dates are counted from the 30%-risk frost dates above (last frost Jan 22, first frost Dec 10). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Nov 27 – Dec 11 | Jan 29 – Feb 12 | — | — |
| Pepper | Nov 13 – Nov 27 | Feb 5 – Feb 19 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 11 – Dec 25 | Jan 8 – Jan 29 | Dec 25 – Feb 5 | Oct 1 – Oct 29 |
| Green Beans | — | — | Jan 29 – Mar 5 | Sep 17 – Oct 1 |
| Sweet Corn | — | — | Jan 29 – Feb 26 | — |
| Zucchini & Summer Squash | Dec 25 – Jan 1 | Jan 29 – Feb 12 | Jan 29 – Feb 19 | Sep 17 – Oct 1 |
| Cucumber | Dec 25 – Jan 1 | Feb 5 – Feb 12 | Jan 29 – Feb 19 | Sep 17 – Oct 1 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 1 – Feb 5 | Sep 17 – Oct 1 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Oct 30 – Nov 13 | Dec 25 – Jan 8 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Dec 25 – Jan 15 | — | — |
| Basil | Dec 11 – Dec 25 | Feb 5 – Feb 19 | Feb 5 – Feb 26 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 11 – Jan 8 | Oct 15 – Nov 12 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 27 – Dec 11 | Dec 25 – Jan 15 | Dec 25 – Jan 15 | Oct 1 – Oct 29 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 27 – Dec 11 | Jan 8 – Jan 29 | — | Sep 17 – Oct 1 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 11 – Jan 1 | Oct 1 – Oct 15 |
| Eggplant | Nov 13 – Nov 27 | Feb 5 – Feb 19 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 27 – Dec 11 | Dec 25 – Jan 8 | — | Sep 17 – Oct 1 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 18 – Feb 5 | Oct 29 – Nov 26 |
| Strawberry | — | Dec 25 – Jan 15 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 1 – Feb 12 | Oct 1 – Oct 15 |
Nearby cities in California
- Pittsburg — zone 9b, last frost Jan 22, first frost Dec 10
- Concord — zone 9b, last frost Jan 23, first frost Dec 6
- San Ramon — zone 9b, last frost Feb 28, first frost Nov 25
- Livermore — zone 9b, last frost Feb 28, first frost Nov 25
- Fairfield — zone 9b, last frost Jan 28, first frost Dec 7
- Vacaville — zone 9b, last frost Mar 3, first frost Nov 21
More: all California cities · other zone 9b cities: Houston, TX, Phoenix, AZ, Jacksonville, FL, San Jose, CA, Fresno, CA, Sacramento, CA, Mesa, AZ, Bakersfield, CA
Antioch gardening questions
When is the last frost in Antioch, CA?
Plan around Jan 22. At NOAA's Antioch Pumping Plt #3, CA station, 2.4 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Jan 12, and after Feb 1 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Jan 2. The 90% and 10% dates are 43 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Antioch, CA?
Start seeds indoors Nov 27 – Dec 11 and set transplants outside Jan 29 – Feb 12, once nights stay above 50°F and the soil is near 60°F. With about 322 frost-free days, frost is not the main limit — fruit set drops when nights stay above about 75°F, so early plantings tend to do best. More: tomato planting dates by zone.
How long is the growing season in Antioch?
About 343 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 315 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Nov 29 and a 30% chance by Dec 10. That ranks 41st longest of 84 California cities on this site.
When should I plant a fall garden in Antioch?
Count back from the first fall frost (Dec 10): transplant broccoli Sep 17 – Oct 1; sow kale Oct 1 – Oct 29; sow lettuce Oct 1 – Oct 29; sow radishes Oct 29 – Nov 26. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 29. How the math works: succession and fall planting.
Did Antioch's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Antioch is zone 9b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does Antioch compare with Concord, CA?
Both are in zone 9b. The typical last spring frost in Antioch (Jan 22) comes about the same time as in Concord, CA (Jan 23), 11 miles away, and the first fall frost is Dec 10 versus Dec 6. The two cities use different NOAA stations.