When is the last frost in San Mateo, CA?

Frost occurs in about 12% of years at the nearest NOAA station (San Francisco Intl Ap, CA), so there is no reliable average last frost date.

When is the first frost in San Mateo, CA?

Frost occurs in about 12% of years at the nearest NOAA station.

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 94402San Mateo, CA

Frost occurs in about 12% of years near San Mateo, based on NOAA 1991-2020 records for the San Francisco Intl Ap, CA station.

Frost occurs in about 12% of years. Frost-tender plants can usually grow year-round, but cover them if a rare cold snap is forecast.

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)	Dec 16 · Jan 8 · Feb 14	Dec 5 · Dec 24 · Jan 24	353 days	70%
Frost / freeze (32°F)	Dec 11 · Dec 29 · Jan 13	Dec 11 · Dec 26 · Jan 13	365 days	12%
Hard freeze (28°F)	—	—	365 days	0%

Where these dates come from

ZIP code 94402 is matched to the NOAA station San Francisco Intl Ap, CA, 8.3 km away, at 8 ft elevation (84 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
San Francisco Intl Ap, CA (used)	8 ft	Dec 29	Dec 26
Redwood City, CA	31 ft	Jan 17	Dec 12
Half Moon Bay, CA	27 ft	Feb 6	Dec 17
Pacifica 4 Sse, CA	475 ft	Jan 11	Jan 10

Frost dates near San Mateo

San Mateo, CA 94497 · last Feb 25, first Nov 25
Burlingame, CA 94010 · last Dec 29, first Dec 26
Belmont, CA 94002 · last Jan 17, first Dec 12
Redwood City, CA 94065 · last Jan 17, first Dec 12
San Carlos, CA 94070 · last Jan 17, first Dec 12
Millbrae, CA 94030 · last Dec 29, first Dec 26
San Francisco, CA 94128 · last Dec 29, first Dec 26
San Bruno, CA 94066 · last Dec 29, first Dec 26

Frequently asked questions

When is the last frost in San Mateo, CA?: Frost occurs in about 12% of years at the nearest NOAA station (San Francisco Intl Ap, CA), so there is no reliable average last frost date.
When is the first frost in San Mateo, CA?: Frost occurs in about 12% of years at the nearest NOAA station.
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.