Redwood City, California: planting zone & frost dates
Redwood City is in USDA plant hardiness zone 10a, where the average coldest winter night reaches 30 to 35°F (-1.1 to 1.7°C). The typical last spring frost is around Jan 31 and the first fall frost around Dec 4.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Feb 16 | Nov 24 |
| Typical planning date (30% risk) | Jan 31 | Dec 4 |
| Median (50%) | Jan 17 | Dec 12 |
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 REDWOOD CITY, CA (USC00047339), 3.0 mi (4.8 km) from the city center and 23 ft higher than the city center (+7 m). Record used for the 1991–2020 normals: 29 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Redwood City
All 4 ZIP codes covering Redwood City are in zone 10a.
Vegetable planting calendar for Redwood City
Dates are counted from the 30%-risk frost dates above (last frost Jan 31, first frost Dec 4). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Dec 6 – Dec 20 | Feb 7 – Feb 21 | — | — |
| Pepper | Nov 22 – Dec 6 | Feb 14 – Feb 28 | — | — |
| Lettuce Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 20 – Jan 3 | Jan 17 – Feb 7 | Jan 3 – Feb 14 | Sep 25 – Oct 23 |
| Green Beans | — | — | Feb 7 – Mar 14 | Sep 11 – Sep 25 |
| Sweet Corn | — | — | Feb 7 – Mar 7 | — |
| Zucchini & Summer Squash | Jan 3 – Jan 10 | Feb 7 – Feb 21 | Feb 7 – Feb 28 | Sep 11 – Sep 25 |
| Cucumber | Jan 3 – Jan 10 | Feb 14 – Feb 21 | Feb 7 – Feb 28 | Sep 11 – Sep 25 |
| Carrot Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 10 – Feb 14 | Sep 11 – Sep 25 |
| Onion Mild winters: fall and winter plantings are usually more reliable than spring. | Nov 8 – Nov 22 | Jan 3 – Jan 17 | — | — |
| Potato Mild winters: fall and winter plantings are usually more reliable than spring. | — | Jan 3 – Jan 24 | — | — |
| Basil | Dec 20 – Jan 3 | Feb 14 – Feb 28 | Feb 14 – Mar 7 | — |
| Spinach Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 20 – Jan 17 | Oct 9 – Nov 6 |
| Kale Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 6 – Dec 20 | Jan 3 – Jan 24 | Jan 3 – Jan 24 | Sep 25 – Oct 23 |
| Broccoli Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 6 – Dec 20 | Jan 17 – Feb 7 | — | Sep 11 – Sep 25 |
| Peas Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 20 – Jan 10 | Sep 25 – Oct 9 |
| Eggplant | Nov 22 – Dec 6 | Feb 14 – Feb 28 | — | — |
| Cabbage Mild winters: fall and winter plantings are usually more reliable than spring. | Dec 6 – Dec 20 | Jan 3 – Jan 17 | — | Sep 11 – Sep 25 |
| Radish Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Dec 27 – Feb 14 | Oct 23 – Nov 20 |
| Strawberry | — | Jan 3 – Jan 24 | — | — |
| Beets Mild winters: fall and winter plantings are usually more reliable than spring. | — | — | Jan 10 – Feb 21 | Sep 25 – Oct 9 |
Nearby cities in California
- San Mateo — zone 10a, last frost Jan 3, first frost Dec 21
- Hayward — zone 10a, last frost Jan 12, first frost Dec 17
- Mountain View — zone 10a, last frost Jan 18, first frost Dec 15
- San Leandro — zone 10a, last frost Jan 22, first frost Dec 10
- Sunnyvale — zone 9b, last frost Jan 18, first frost Dec 15
- Alameda — zone 10a, last frost Jan 22, first frost Dec 10
More: all California cities · other zone 10a cities: Los Angeles, CA, Oakland, CA, Tampa, FL, Orlando, FL, Riverside, CA, Corpus Christi, TX, Port St. Lucie, FL, Scottsdale, AZ
Redwood City gardening questions
When is the last frost in Redwood City, CA?
Plan around Jan 31. At NOAA's Redwood City, CA station, 3.0 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 17, and after Feb 16 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Dec 31. Springs here are erratic: 58 days separate the 90% and 10% dates, versus a median of 36 days for cities on this site, so watch the forecast rather than the calendar.
When should I plant tomatoes in Redwood City, CA?
Start seeds indoors Dec 6 – Dec 20 and set transplants outside Feb 7 – Feb 21, once nights stay above 50°F and the soil is near 60°F. With about 307 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 Redwood City?
About 333 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 298 days, and in 1 year in 10 it runs 365 days or more. In fall there is a 10% chance of frost by Nov 24 and a 30% chance by Dec 4. That ranks 52nd longest of 84 California cities on this site.
When should I plant a fall garden in Redwood City?
Count back from the first fall frost (Dec 4): transplant broccoli Sep 11 – Sep 25; sow kale Sep 25 – Oct 23; sow lettuce Sep 25 – Oct 23; sow radishes Oct 23 – Nov 20. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 26. How the math works: succession and fall planting.
Did Redwood City's hardiness zone change on the 2023 map?
Yes. Most of Redwood City was zone 9b on the 2012 map and is zone 10a on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Redwood City compare with San Mateo, CA?
Both are in zone 10a. The typical last spring frost in Redwood City (Jan 31) comes about 28 days later than in San Mateo, CA (Jan 3), 6 miles away, and the first fall frost is Dec 4 versus Dec 21. The two cities use different NOAA stations.