Frost Dates for Rohnert Park, CA 94928

Last spring frost February 28 · First fall frost November 27 · 272 frost-free days · USDA Zone 9a

Frost probability for 94928

Frost10%50%90%
Spring (last frost)April 15February 28January 13
Fall (first frost)October 29November 27November 23

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (12.3 km away); the 50% date is the median year.

Month by month in Rohnert Park

MonthWhat to do
JanuaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
FebruaryLast frost around February 28. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MarchFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
AprilSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
MayHarvest regularly to encourage production. Monitor for pests and disease.
JuneMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
JulyDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberFirst fall frost approaching (around November 27). Transplant fall brassicas. Sow spinach, arugula, and radishes.
NovemberFirst frost around November 27. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
DecemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.

What grows in a 272-day season

Frequently Asked Questions

What is the last frost date for Rohnert Park, CA (ZIP 94928)?

The median last spring frost date for Rohnert Park, CA (ZIP code 94928) is around February 28. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Rohnert Park, CA?

The median first fall frost date for Rohnert Park, CA is around November 27. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Rohnert Park, CA?

The frost-free growing season in Rohnert Park is about 272 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Rohnert Park, CA?

Based on frost date patterns, Rohnert Park falls approximately in 9a. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Rohnert Park, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around February 28). For Rohnert Park, that's roughly January 3 to January 17. Transplant outdoors 1–2 weeks after your last frost.

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