Frost Dates for Greenbrae, CA 94904

Last spring frost January 24 · First fall frost January 2 · 343 frost-free days · USDA Zone 9b

Frost probability for 94904

Frost10%50%90%
Spring (last frost)March 15January 24—
Fall (first frost)November 19January 2—

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (5.7 km away); the 50% date is the median year.

Month by month in Greenbrae

MonthWhat to do
JanuaryPlant cool-season crops: lettuce, spinach, broccoli, peas, and carrots.
FebruaryDirect sow brassicas and root vegetables. Start warm-season seedlings indoors.
MarchTransplant warm-season crops outdoors. Sow beans, cucumbers, and squash.
AprilMain warm-season planting window. Direct sow melons and sweet corn.
MaySuccession plant lettuce. Keep beds irrigated as temperatures climb.
JuneMonitor for heat stress. Harvest zucchini and cucumbers frequently.
JulyHarvest regularly to encourage continued production. Watch for pests.
AugustStart fall cool-season crops: broccoli, kale, beets, and carrots.
SeptemberPlant fall lettuce, spinach, arugula, and radishes.
OctoberHarvest mature crops. Direct sow cold-tolerant greens.
NovemberPlant garlic and onion sets. Harvest cool-season crops through the month.
DecemberPlant cool-season crops for winter harvest. Plan next year's garden.

What grows in a 343-day season

Frequently Asked Questions

What is the last frost date for Greenbrae, CA (ZIP 94904)?

The median last spring frost date for Greenbrae, CA (ZIP code 94904) is around January 24. 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 Greenbrae, CA?

The median first fall frost date for Greenbrae, CA is around January 2. 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 Greenbrae, CA?

The frost-free growing season in Greenbrae is about 343 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 Greenbrae, CA?

Based on frost date patterns, Greenbrae falls approximately in 9b. 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 Greenbrae, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around January 24). For Greenbrae, that's roughly November 29 to December 13. Transplant outdoors 1–2 weeks after your last frost.

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