Rio Oso, CA frost dates
Last spring frostFeb 11median date
First fall frostNov 30median date
Growing season292 daysfrost-free
Hardiness zone9bZone 9b
How Rio Oso compares
- In 8 years out of 10, the last spring frost in Rio Oso falls between January 6 and March 12, a 65-day window. The first fall frost falls between November 12 and December 21.
- The median last frost is 48 days earlier than the California median of Mar 31.
- Its 292-day growing season is longer than 94% of the 636 California places with a regular frost season (state median 235 days).
- The last frost is 9 days earlier 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 23 nights a year at or below 32°F.
- Rio Oso shares its weather station with Yuba City, CA, 19 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | January 6 |
| 50% (median) | February 11 |
| 10% (safe for tender plants) | March 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 12 |
| 50% (median) | November 30 |
| 90% (late) | December 21 |
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 Rio Oso, CA
Rio Oso, CA frost dates — last frost Feb 11, first frost Nov 30, zone 9b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Nov 19 to Dec 3Transplant outside: Jan 14 to Jan 28
Start indoors: Dec 3 to Dec 17Transplant outside: Feb 25 to Mar 11
Start indoors: Dec 3 to Dec 17Transplant outside: Feb 25 to Mar 11
Start indoors: Dec 17 to Dec 31Transplant outside: Feb 18 to Mar 4
Start indoors: Dec 17 to Dec 31Transplant outside: Jan 21 to Feb 4Sow outdoors: Jan 14 to Feb 18Plant for fall: Oct 5 to Nov 2
Start indoors: Dec 17 to Dec 31Transplant outside: Jan 14 to Jan 28Sow outdoors: Jan 14 to Jan 28Plant for fall: Sep 21 to Oct 12
Start indoors: Dec 17 to Dec 31Transplant outside: Jan 28 to Feb 11Plant for fall: Aug 24 to Sep 14
Start indoors: Dec 17 to Dec 31Transplant outside: Jan 21 to Feb 4Plant for fall: Aug 24 to Sep 14
Start indoors: Dec 17 to Dec 31Transplant outside: Jan 28 to Feb 11Plant for fall: Aug 24 to Sep 14
Start indoors: Dec 31 to Jan 14Start indoors: Dec 31 to Jan 14Transplant outside: Mar 4 to Mar 18Sow outdoors: Mar 4 to Mar 18
Start indoors: Dec 31 to Jan 14Start indoors: Dec 31 to Jan 14Transplant outside: Feb 18 to Mar 4
Sow outdoors: Dec 31 to Jan 21Sow outdoors: Dec 31 to Jan 21Plant for fall: Sep 7 to Sep 28
Sow outdoors: Dec 31 to Jan 21Sow outdoors: Dec 31 to Jan 21Plant for fall: Oct 5 to Oct 26
Sow outdoors: Jan 7 to Feb 18Plant for fall: Oct 19 to Nov 9
Start indoors: Jan 14 to Jan 21Transplant outside: Feb 25 to Mar 4Sow outdoors: Feb 18 to Mar 4Plant for fall: Sep 14 to Sep 28
Start indoors: Jan 14 to Jan 21Sow outdoors: Feb 18 to Mar 4Plant for fall: Sep 21 to Oct 5
Start indoors: Jan 14 to Jan 21Sow outdoors: Feb 18 to Mar 4
Start indoors: Jan 14 to Jan 21Transplant outside: Feb 25 to Mar 11
Sow outdoors: Jan 21 to Feb 18Plant for fall: Sep 7 to Sep 21
Sow outdoors: Jan 21 to Feb 18Plant for fall: Sep 21 to Oct 5
Sow outdoors: Jan 21 to Feb 11
Sow outdoors: Jan 28 to Feb 25Plant for fall: Sep 21 to Oct 5
Sow outdoors: Jan 28 to Feb 18Plant for fall: Oct 5 to Oct 26
Sow outdoors: Feb 18 to Mar 11Plant for fall: Sep 14 to Sep 28
Sow outdoors: Feb 18 to Mar 4
Transplant outside: Feb 25 to Mar 18
Plant for fall: Nov 16 to Dec 21
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Rio Oso, CA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Nov 19 – Dec 3 | Jan 14 – Jan 28 | — | — |
| Peppers | Dec 3 – Dec 17 | Feb 25 – Mar 11 | — | — |
| Eggplant | Dec 3 – Dec 17 | Feb 25 – Mar 11 | — | — |
| Tomatoes | Dec 17 – Dec 31 | Feb 18 – Mar 4 | — | — |
| Lettuce | Dec 17 – Dec 31 | Jan 21 – Feb 4 | Jan 14 – Feb 18 | Oct 5 – Nov 2 |
| Kale | Dec 17 – Dec 31 | Jan 14 – Jan 28 | Jan 14 – Jan 28 | Sep 21 – Oct 12 |
| Broccoli | Dec 17 – Dec 31 | Jan 28 – Feb 11 | — | Aug 24 – Sep 14 |
| Cabbage | Dec 17 – Dec 31 | Jan 21 – Feb 4 | — | Aug 24 – Sep 14 |
| Cauliflower | Dec 17 – Dec 31 | Jan 28 – Feb 11 | — | Aug 24 – Sep 14 |
| Okra | Dec 31 – Jan 14 | Mar 4 – Mar 18 | Mar 4 – Mar 18 | — |
| Basil | Dec 31 – Jan 14 | Feb 18 – Mar 4 | — | — |
| Peas | — | — | Dec 31 – Jan 21 | Sep 7 – Sep 28 |
| Spinach | — | — | Dec 31 – Jan 21 | Oct 5 – Oct 26 |
| Radishes | — | — | Jan 7 – Feb 18 | Oct 19 – Nov 9 |
| Cucumbers | Jan 14 – Jan 21 | Feb 25 – Mar 4 | Feb 18 – Mar 4 | Sep 14 – Sep 28 |
| Zucchini & Summer Squash | Jan 14 – Jan 21 | — | Feb 18 – Mar 4 | Sep 21 – Oct 5 |
| Winter Squash & Pumpkins | Jan 14 – Jan 21 | — | Feb 18 – Mar 4 | — |
| Melons & Watermelon | Jan 14 – Jan 21 | Feb 25 – Mar 11 | — | — |
| Carrots | — | — | Jan 21 – Feb 18 | Sep 7 – Sep 21 |
| Beets | — | — | Jan 21 – Feb 18 | Sep 21 – Oct 5 |
| Potatoes | — | — | Jan 21 – Feb 11 | — |
| Swiss Chard | — | — | Jan 28 – Feb 25 | Sep 21 – Oct 5 |
| Cilantro | — | — | Jan 28 – Feb 18 | Oct 5 – Oct 26 |
| Green Beans | — | — | Feb 18 – Mar 11 | Sep 14 – Sep 28 |
| Sweet Corn | — | — | Feb 18 – Mar 4 | — |
| Sweet Potatoes | — | Feb 25 – Mar 18 | — | — |
| Garlic | — | — | — | Nov 16 – Dec 21 |
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 Marysville Yuba Co Ap, CA weather station, 17 km away (elevation 62 ft (19 m)).
Frost dates near Rio Oso
- Wheatland Feb 11 · Nov 30
- Sheridan Feb 11 · Nov 30
- Nicolaus Feb 22 · Nov 24
- Olivehurst Feb 11 · Nov 30
- Pleasant Grove Feb 22 · Nov 24
- Lincoln Feb 25 · Dec 5
- Yuba City Feb 11 · Nov 30
- Beale Afb Feb 11 · Nov 30
- Marysville Jan 15 · Dec 12
- Robbins Feb 22 · Nov 24
Frequently asked questions
When is the last frost in Rio Oso, CA?
The median last spring frost in Rio Oso, CA is February 11. There is still about a 10% chance of frost after March 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Rio Oso, CA?
The median first fall frost is November 30, with about a 10% chance of frost before November 12.
How long is the growing season in Rio Oso, CA?
About 292 days between the median last spring frost and first fall frost.
What planting zone is Rio Oso, CA?
Rio Oso, CA is in USDA hardiness zone 9b.