When is the last frost in San Rafael, CA?

The average last spring frost (50% probability of 32°F) in San Rafael is around January 11, based on NOAA/NCEI 1991–2020 normals at the San Rafael Civic Ctr, CA station (2 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in San Rafael?

The average first fall frost in San Rafael, CA is around December 21, giving roughly a 349-day frost-free growing season.

What planting zone is San Rafael, CA?

San Rafael is in USDA plant hardiness zone 9b (average annual extreme minimum temperature 25 to 30°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in San Rafael?

In San Rafael, CA the warmest month is August (avg high 81.3°F) and the coldest is December (avg low 42.1°F). It averages about 34.5″ of precipitation a year.

Home › California › San Rafael

San Rafael, CA Planting Calendar & Frost Dates

USDA hardiness zone 9b · ZIP 94903 · elevation 37′ · NOAA & USDA data

San Rafael is in USDA hardiness zone 9b (winters can dip to 25 to 30°F), with a growing season of about 349 days between the average last spring frost (January 11) and first fall frost (December 21). The warmest month is August (avg high 81.3°F); the coldest is December (avg low 42.1°F). It averages 34.5″ of precipitation a year. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp 25 to 30°F

Last spring frost

January 11

avg (50% prob, 32°F)

First fall frost

December 21

avg (50% prob, 32°F)

Growing season

349 days

frost-free window

Warmest month

August

avg high 81.3°F

Month-by-month typical weather in San Rafael

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at San Rafael Civic Ctr, CA (2 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)
January	56.9	42.6	49.8	7.1
February	61.1	44	52.5	6.9
March	64.8	45.5	55.2	4.4
April	67.8	47.5	57.7	2
May	72	50.6	61.3	0.9
June	77.9	53.5	65.7	0.2
July	80.9	54.9	67.9	0
August	81.3	55.5	68.4	0.1
September	80.7	54.4	67.6	0.1
October	74.9	51.4	63.2	1.5
November	64.6	46	55.3	3.5
December	57.1	42.1	49.6	7.8

What to plant when in San Rafael

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: November 30 · Transplant out: January 18
Peppers	warm	Start seeds indoors: November 16 · Transplant out: January 25
Cucumbers	warm	Direct sow: January 18
Zucchini / squash	warm	Direct sow: January 18
Bush beans	warm	Direct sow: January 18
Sweet corn	warm	Direct sow: January 18
Basil	warm	Transplant out: January 18
Peas	cool	Sow (spring): December 7 · Sow (fall): October 26
Spinach	cool	Sow (spring): November 30 · Sow (fall): October 26
Lettuce	cool	Sow (spring): December 14 · Sow (fall): October 26
Kale	cool	Transplant (spring): December 21 · Sow (fall): October 12
Broccoli	cool	Transplant (spring): December 28
Carrots	cool	Sow (spring): December 21 · Sow (fall): October 12
Onions	cool	Transplant (spring): December 14
Potatoes	cool	Plant seed potatoes: December 28
Radishes	cool	Sow (spring): December 14 · Sow (fall): November 9

Dates are computed from San Rafael's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in California

Novato, CA Richmond, CA Vallejo, CA Petaluma, CA Berkeley, CA San Francisco, CA Martinez, CA Alameda, CA

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — San Rafael Civic Ctr, CA, 2 mi (confidence: high). Monthly weather normals: San Rafael Civic Ctr, CA, 2 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.