When is the last frost in San Rafael, CA?

For ZIP code 94901, the average last spring frost (32°F) is January 11, based on NOAA 1991-2020 climate normals for the San Rafael Civic Ctr, CA weather station. There is a 1-in-10 chance of a frost after February 25.

When is the first frost in San Rafael, CA?

The average first fall frost (32°F) is December 21. There is a 1-in-10 chance of frost by December 2, so tender plants are at risk from that point on.

How long is the growing season in 94901?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 349 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.

Frost dates for 94901San Rafael, CA

The average last spring frost in San Rafael is January 11 and the average first fall frost is December 21, giving a typical growing season of about 349 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 11
Average first fall frost: Dec 21
Growing season: 349 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.

Spring dates: chance of a frost AFTER the date. Fall dates: chance of a frost BEFORE the date.
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)	Jan 6 · Feb 22 · Apr 6	Nov 15 · Dec 5 · Jan 1	287 days	99%
Frost / freeze (32°F)	Dec 14 · Jan 11 · Feb 25	Dec 2 · Dec 21 · Feb 9	349 days	70%
Hard freeze (28°F)	Dec 11 · Dec 31 · Feb 21	Dec 7 · Dec 29 · Feb 18	365 days	21%

Where these dates come from

ZIP code 94901 is matched to the NOAA station San Rafael Civic Ctr, CA, 4 km away, at 120 ft elevation (28 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
San Rafael Civic Ctr, CA (used)	120 ft	Jan 11	Dec 21
Kentfield, CA	145 ft	Jan 16	Dec 18
Richmond, CA	20 ft	Jan 4	Jan 2
San Francisco Dwtn, CA	150 ft	—	—

Frost dates near San Rafael

San Rafael, CA 94912 · last Jan 11, first Dec 21
Greenbrae, CA 94904 · last Jan 16, first Dec 18
San Quentin, CA 94974 · last Jan 4, first Jan 2
Ross, CA 94957 · last Jan 16, first Dec 18
Larkspur, CA 94939 · last Jan 16, first Dec 18
Kentfield, CA 94914 · last Jan 16, first Dec 18
San Anselmo, CA 94979 · last Jan 11, first Dec 21
Corte Madera, CA 94976 · last Jan 16, first Dec 18

Frequently asked questions

When is the last frost in San Rafael, CA?: For ZIP code 94901, the average last spring frost (32°F) is January 11, based on NOAA 1991-2020 climate normals for the San Rafael Civic Ctr, CA weather station. There is a 1-in-10 chance of a frost after February 25.
When is the first frost in San Rafael, CA?: The average first fall frost (32°F) is December 21. There is a 1-in-10 chance of frost by December 2, so tender plants are at risk from that point on.
How long is the growing season in 94901?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 349 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.