Frost dates for 94926Rohnert Park, CA
The average last spring frost in Rohnert Park is February 25 and the average first fall frost is December 1, giving a typical growing season of about 279 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Feb 25
- Average first fall frost
- Dec 1
- Growing season
- 279 days
Safer after Mar 29 (1-in-10 risk)
Possible by Nov 10 (1-in-10 risk)
First frost typically in 28 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) | Mar 6 · Apr 3 · Apr 25 | Oct 31 · Nov 14 · Dec 1 | 223 days | 100% |
| Frost / freeze (32°F) | Jan 21 · Feb 25 · Mar 29 | Nov 10 · Dec 1 · Dec 24 | 279 days | 99% |
| Hard freeze (28°F) | Dec 22 · Jan 20 · Feb 24 | Nov 26 · Dec 16 · Jan 19 | 335 days | 83% |
Planting calendar for Rohnert Park
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 25 – Apr 2 |
| Tomatoes | Transplant outdoors | Mar 13 – Aug 11 |
| Peppers | Start seeds indoors | Jan 25 – Feb 25 |
| Peppers | Transplant outdoors | Mar 27 – Apr 27 |
| Eggplant | Start seeds indoors | Feb 11 – Mar 12 |
| Eggplant | Transplant outdoors | Mar 27 – Apr 27 |
| Cucumbers | Sow outdoors | Mar 27 – Aug 21 |
| Summer squash | Sow outdoors | Mar 13 – Apr 27 |
| Winter squash & pumpkins | Sow outdoors | Mar 27 – Apr 27 |
| Snap beans | Sow outdoors | Mar 13 – Sep 13 |
| Sweet corn | Sow outdoors | Mar 13 – Aug 11 |
| Watermelon & cantaloupe | Sow outdoors | Mar 27 – Apr 27 |
| Okra | Sow outdoors | Mar 20 – Apr 12 |
| Peas | Sow outdoors (spring) | Jan 25 – Mar 12 |
| Potatoes | Plant outdoors (spring) | Jan 25 – Mar 27 |
| Onions | Start seeds indoors (spring) | Dec 14 – Jan 10 |
| Onions | Transplant outdoors (spring) | Feb 11 – Mar 12 |
| Broccoli | Start seeds indoors (spring) | Jan 7 – Feb 10 |
| Broccoli | Transplant outdoors (spring) | Feb 11 – Mar 12 |
| Broccoli | Start seeds indoors (fall) | Aug 1 – Aug 11 |
| Broccoli | Transplant outdoors (fall) | Aug 31 – Sep 11 |
| Cabbage | Start seeds indoors (spring) | Dec 28 – Jan 25 |
| Cabbage | Transplant outdoors (spring) | Jan 25 – Feb 25 |
| Cabbage | Start seeds indoors (fall) | Jul 22 – Aug 21 |
| Cabbage | Transplant outdoors (fall) | Aug 21 – Sep 21 |
| Leaf lettuce | Sow outdoors (spring) | Jan 25 – Apr 12 |
| Leaf lettuce | Sow outdoors (fall) | Aug 21 – Oct 7 |
| Spinach | Sow outdoors (spring) | Jan 18 – Mar 3 |
| Spinach | Sow outdoors (fall) | Sep 7 – Oct 12 |
| Radishes | Sow outdoors (spring) | Jan 25 – Mar 17 |
| Radishes | Sow outdoors (fall) | Aug 21 – Oct 22 |
| Kale | Sow outdoors (spring) | Feb 11 – Mar 3 |
| Kale | Sow outdoors (fall) | Aug 14 – Sep 21 |
| Carrots | Sow outdoors (spring) | Feb 25 – Apr 12 |
| Carrots | Sow outdoors (fall) | Jul 22 – Sep 6 |
| Garlic | Plant outdoors (fall) | Nov 21 – Dec 22 |
Where these dates come from
ZIP code 94926 is matched to the NOAA station Santa Rosa, CA, 13 km away, at 166 ft elevation (61 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Santa Rosa, CA (used) | 166 ft | Feb 25 | Dec 1 |
| Petaluma Ap, CA | 20 ft | Feb 28 | Nov 25 |
| Graton, CA | 200 ft | Mar 20 | Nov 13 |
| Santa Rosa Sonoma Co Ap, CA | 114 ft | Mar 2 | Nov 20 |
Frost dates near Rohnert Park
- Rohnert Park, CA 94927 · last Feb 25, first Dec 1
- Cotati, CA 94931 · last Feb 28, first Nov 25
- Penngrove, CA 94951 · last Feb 28, first Nov 25
- Santa Rosa, CA 95407 · last Feb 25, first Dec 1
- Petaluma, CA 94999 · last Feb 28, first Nov 25
- Sebastopol, CA 95473 · last Mar 20, first Nov 13
- Kenwood, CA 95452 · last Feb 3, first Dec 4
- Glen Ellen, CA 95442 · last Mar 2, first Nov 27
Frequently asked questions
- When is the last frost in Rohnert Park, CA?
- For ZIP code 94926, the average last spring frost (32°F) is February 25, based on NOAA 1991-2020 climate normals for the Santa Rosa, CA weather station. There is a 1-in-10 chance of a frost after March 29.
- When is the first frost in Rohnert Park, CA?
- The average first fall frost (32°F) is December 1. There is a 1-in-10 chance of frost by November 10, so tender plants are at risk from that point on.
- How long is the growing season in 94926?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 279 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.