When is the last frost in San Gregorio, CA?

For ZIP code 94074, the average last spring frost (32°F) is February 6, based on NOAA 1991-2020 climate normals for the Half Moon Bay, CA weather station. There is a 1-in-10 chance of a frost after March 25.

When is the first frost in San Gregorio, CA?

The average first fall frost (32°F) is December 17. There is a 1-in-10 chance of frost by November 25, so tender plants are at risk from that point on.

How long is the growing season in 94074?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 328 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 94074San Gregorio, CA

The average last spring frost in San Gregorio is February 6 and the average first fall frost is December 17, giving a typical growing season of about 328 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Feb 6
Average first fall frost: Dec 17
Growing season: 328 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)	Feb 23 · Apr 3 · May 1	Oct 20 · Nov 20 · Dec 16	230 days	100%
Frost / freeze (32°F)	Dec 17 · Feb 6 · Mar 25	Nov 25 · Dec 17 · Feb 13	328 days	82%
Hard freeze (28°F)	Dec 5 · Jan 5 · Feb 26	Dec 4 · Dec 31 · Feb 23	365 days	19%

Where these dates come from

ZIP code 94074 is matched to the NOAA station Half Moon Bay, CA, 18.1 km away, at 27 ft elevation (68 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Half Moon Bay, CA (used)	27 ft	Feb 6	Dec 17
San Gregorio 2 Se, CA	275 ft	Mar 2	Nov 25
Woodside Fire Stn 1, CA	380 ft	Feb 25	Nov 25
Skyline Ridge Preserve, CA	2,270 ft	Mar 21	Dec 15

Frost dates near San Gregorio

Menlo Park, CA 94026 · last Feb 25, first Nov 25
Redwood City, CA 94064 · last Feb 25, first Nov 25
Loma Mar, CA 94021 · last Feb 25, first Nov 25
La Honda, CA 94020 · last Feb 25, first Nov 25
Portola Valley, CA 94028 · last Feb 25, first Nov 25
Pescadero, CA 94060 · last Mar 2, first Nov 25
Half Moon Bay, CA 94019 · last Feb 6, first Dec 17
Palo Alto, CA 94304 · last Feb 1, first Dec 7

Frequently asked questions

When is the last frost in San Gregorio, CA?: For ZIP code 94074, the average last spring frost (32°F) is February 6, based on NOAA 1991-2020 climate normals for the Half Moon Bay, CA weather station. There is a 1-in-10 chance of a frost after March 25.
When is the first frost in San Gregorio, CA?: The average first fall frost (32°F) is December 17. There is a 1-in-10 chance of frost by November 25, so tender plants are at risk from that point on.
How long is the growing season in 94074?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 328 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.