Cobb, CA frost dates
Last spring frostApr 10median date
First fall frostNov 6median date
Growing season210 daysfrost-free
Hardiness zone9bZone 9b
How Cobb compares
- In 8 years out of 10, the last spring frost in Cobb falls between March 24 and April 30, a 37-day window. The first fall frost falls between October 24 and November 20.
- The median last frost is 10 days later than the California median of Mar 31.
- Its 210-day growing season is longer than 37% of the 636 California places with a regular frost season (state median 235 days).
- The last frost is 49 days later than the zone 9b median of Feb 20. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 9b chart.
- The weather station records an average of 72 nights a year at or below 32°F.
- Compared with Santa Rosa, CA, 41 km away, the last frost here is 44 days later than there and the growing season is 69 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | March 24 |
| 50% (median) | April 10 |
| 10% (safe for tender plants) | April 30 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 24 |
| 50% (median) | November 6 |
| 90% (late) | November 20 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Cobb, CA
Cobb, CA frost dates — last frost Apr 10, first frost Nov 6, zone 9b. whenisthelastfrost.com
Crop
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Start indoors: Jan 16 to Jan 30Transplant outside: Mar 13 to Mar 27
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Jan 30 to Feb 13Transplant outside: Apr 24 to May 8
Start indoors: Feb 13 to Feb 27Transplant outside: Apr 17 to May 1
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Sow outdoors: Mar 13 to Apr 17Plant for fall: Sep 11 to Oct 9
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 13 to Mar 27Sow outdoors: Mar 13 to Mar 27Plant for fall: Aug 28 to Sep 18
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 31 to Aug 21
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 20 to Apr 3Plant for fall: Jul 31 to Aug 21
Start indoors: Feb 13 to Feb 27Transplant outside: Mar 27 to Apr 10Plant for fall: Jul 31 to Aug 21
Start indoors: Feb 27 to Mar 13Transplant outside: May 1 to May 15Sow outdoors: May 1 to May 15
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 17 to May 1
Sow outdoors: Feb 27 to Mar 20Plant for fall: Aug 14 to Sep 4
Sow outdoors: Feb 27 to Mar 20Plant for fall: Sep 11 to Oct 2
Sow outdoors: Mar 6 to Apr 17Plant for fall: Sep 25 to Oct 16
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 1Sow outdoors: Apr 17 to May 1Plant for fall: Aug 21 to Sep 4
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1Plant for fall: Aug 28 to Sep 11
Start indoors: Mar 13 to Mar 20Sow outdoors: Apr 17 to May 1
Start indoors: Mar 13 to Mar 20Transplant outside: Apr 24 to May 8
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 14 to Aug 28
Sow outdoors: Mar 20 to Apr 17Plant for fall: Aug 28 to Sep 11
Sow outdoors: Mar 20 to Apr 10
Sow outdoors: Mar 27 to Apr 24Plant for fall: Aug 28 to Sep 11
Sow outdoors: Mar 27 to Apr 17Plant for fall: Sep 11 to Oct 2
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 21 to Sep 4
Sow outdoors: Apr 17 to May 1
Transplant outside: Apr 24 to May 15
Plant for fall: Oct 23 to Nov 27
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Cobb, CA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 16 – Jan 30 | Mar 13 – Mar 27 | — | — |
| Peppers | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Eggplant | Jan 30 – Feb 13 | Apr 24 – May 8 | — | — |
| Tomatoes | Feb 13 – Feb 27 | Apr 17 – May 1 | — | — |
| Lettuce | Feb 13 – Feb 27 | Mar 20 – Apr 3 | Mar 13 – Apr 17 | Sep 11 – Oct 9 |
| Kale | Feb 13 – Feb 27 | Mar 13 – Mar 27 | Mar 13 – Mar 27 | Aug 28 – Sep 18 |
| Broccoli | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 31 – Aug 21 |
| Cabbage | Feb 13 – Feb 27 | Mar 20 – Apr 3 | — | Jul 31 – Aug 21 |
| Cauliflower | Feb 13 – Feb 27 | Mar 27 – Apr 10 | — | Jul 31 – Aug 21 |
| Okra | Feb 27 – Mar 13 | May 1 – May 15 | May 1 – May 15 | — |
| Basil | Feb 27 – Mar 13 | Apr 17 – May 1 | — | — |
| Peas | — | — | Feb 27 – Mar 20 | Aug 14 – Sep 4 |
| Spinach | — | — | Feb 27 – Mar 20 | Sep 11 – Oct 2 |
| Radishes | — | — | Mar 6 – Apr 17 | Sep 25 – Oct 16 |
| Cucumbers | Mar 13 – Mar 20 | Apr 24 – May 1 | Apr 17 – May 1 | Aug 21 – Sep 4 |
| Zucchini & Summer Squash | Mar 13 – Mar 20 | — | Apr 17 – May 1 | Aug 28 – Sep 11 |
| Winter Squash & Pumpkins | Mar 13 – Mar 20 | — | Apr 17 – May 1 | — |
| Melons & Watermelon | Mar 13 – Mar 20 | Apr 24 – May 8 | — | — |
| Carrots | — | — | Mar 20 – Apr 17 | Aug 14 – Aug 28 |
| Beets | — | — | Mar 20 – Apr 17 | Aug 28 – Sep 11 |
| Potatoes | — | — | Mar 20 – Apr 10 | — |
| Swiss Chard | — | — | Mar 27 – Apr 24 | Aug 28 – Sep 11 |
| Cilantro | — | — | Mar 27 – Apr 17 | Sep 11 – Oct 2 |
| Green Beans | — | — | Apr 17 – May 8 | Aug 21 – Sep 4 |
| Sweet Corn | — | — | Apr 17 – May 1 | — |
| Sweet Potatoes | — | Apr 24 – May 15 | — | — |
| Garlic | — | — | — | Oct 23 – Nov 27 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Clearlake 4 Se, CA weather station, 17 km away (elevation 1,348 ft (411 m)).
Frost dates near Cobb
- Middletown Apr 10 · Nov 6
- Lower Lake Apr 10 · Nov 6
- Hidden Valley Lake Apr 10 · Nov 6
- Kelseyville Apr 10 · Nov 6
- Clearlake Apr 10 · Nov 6
- Clearlake Park Apr 10 · Nov 6
- Geyserville Feb 15 · Dec 2
- Glenhaven Apr 10 · Nov 6
- Finley Feb 25 · Dec 3
- Healdsburg Feb 15 · Dec 2
Frequently asked questions
When is the last frost in Cobb, CA?
The median last spring frost in Cobb, CA is April 10. There is still about a 10% chance of frost after April 30, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Cobb, CA?
The median first fall frost is November 6, with about a 10% chance of frost before October 24.
How long is the growing season in Cobb, CA?
About 210 days between the median last spring frost and first fall frost.
What planting zone is Cobb, CA?
Cobb, CA is in USDA hardiness zone 9b.