San Francisco, CA Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for San Francisco, California.
Gardening in San Francisco
San Francisco gardening is an exercise in microclimates. Your garden in the Sunset District lives in a different climate than one in the Mission, which is different from one in Potrero Hill, which is different from one in the Bayview. Mark Twain's (probably misattributed) quote about the coldest winter being a summer in San Francisco? Your tomatoes agree.
The fog is the boss. Neighborhoods west of Twin Peaks get socked in during summer, keeping temperatures in the 50s-60s while the East Bay broils at 90°F. This means your Sunset garden grows world-class cool-season crops year-round but struggles with tomatoes. A Mission District garden, sheltered from fog, can actually ripen tomatoes. Frost is nearly unknown, and the 344-day growing season is real — but only for crops that match your specific microclimate.
Giants fans know about thriving in conditions that outsiders find baffling — that's San Francisco gardening in one sentence. The city's community garden movement has deep roots in the Summer of Love era, and Alice Waters' farm-to-table revolution at Chez Panisse (technically Berkeley, but the Bay claims it) inspired a generation of Bay Area gardeners. Your Instagram-perfect raised beds are not performative — they're practically a civic duty.
What This Means for San Francisco Gardeners
The average last spring frost in San Francisco is around January 10, and the average first fall frost arrives around December 20. That gives you approximately 344 frost-free days to work with.
San Francisco's growing season is essentially year-round. Frost is a rare event, not a seasonal boundary. Traditional cool-season crops grow through your mild winter, while tropical and subtropical plants thrive permanently outdoors. Your challenge isn't length of season — it's managing summer heat and humidity. Plant warm-season vegetables from September through February and shift to heat-tolerant crops for the summer months.
These dates are based on NOAA 30-year Climate Normal data for the San Francisco area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in San Francisco
With 344 frost-free days, San Francisco can grow nearly anything — including tropical and subtropical plants that most of the country can only dream about. Your prime vegetable season runs from fall through spring; summer is for heat-lovers like okra, sweet potatoes, and peppers. Recommended starting points: cherry tomatoes, jalapeños, okra, sweet potatoes, basil, collard greens, tomatillos, and lemongrass.
See the full California planting guide for all 40 plants: California Planting Calendar. Or enter your zip code for exact planting dates personalized to San Francisco.
More About Zone 10B
San Francisco is in USDA Hardiness Zone 10B, which means average annual extreme minimum temperatures between 35°F to 40°F. View the full Zone 10B planting guide.
See the complete planting calendar for California: California Planting Calendar.
Other Cities in California
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the San Francisco area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within San Francisco (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
You can plant cool-season crops (lettuce, kale, broccoli) from December 20 through January 10 — your cool season is your primary vegetable season. Warm-season crops like tomatoes and peppers go out in early spring. Tropical plants grow year-round. Enter your zip code for exact dates for every plant.