When is the last frost in Los Altos, CA?

For ZIP code 94023, the average last spring frost (32°F) is January 6, based on NOAA 1991-2020 climate normals for the Moffett Federal Airfield, CA weather station. There is a 1-in-10 chance of a frost after February 4.

When is the first frost in Los Altos, CA?

The average first fall frost (32°F) is December 23. There is a 1-in-10 chance of frost by December 3, so tender plants are at risk from that point on.

How long is the growing season in 94023?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 353 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 94023Los Altos, CA

The average last spring frost in Los Altos is January 6 and the average first fall frost is December 23, giving a typical growing season of about 353 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 6
Average first fall frost: Dec 23
Growing season: 353 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 3 · Feb 6 · Mar 6	Nov 20 · Dec 6 · Dec 30	306 days	99%
Frost / freeze (32°F)	Dec 16 · Jan 6 · Feb 4	Dec 3 · Dec 23 · Jan 16	353 days	70%
Hard freeze (28°F)	Dec 16 · Jan 1 · Jan 22	Dec 13 · Dec 31 · Jan 22	365 days	14%

Where these dates come from

ZIP code 94023 is matched to the NOAA station Moffett Federal Airfield, CA, 6.3 km away, at 39 ft elevation (118 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Moffett Federal Airfield, CA (used)	39 ft	Jan 6	Dec 23
Palo Alto, CA	25 ft	Feb 1	Dec 7
Skyline Ridge Preserve, CA	2,270 ft	Mar 21	Dec 15
Woodside Fire Stn 1, CA	380 ft	Feb 25	Nov 25

Frost dates near Los Altos

Los Altos, CA 94022 · last Jan 6, first Dec 23
Mountain View, CA 94040 · last Jan 6, first Dec 23
Palo Alto, CA 94306 · last Feb 1, first Dec 7
Stanford, CA 94305 · last Feb 1, first Dec 7
Sunnyvale, CA 94088 · last Jan 6, first Dec 23
Cupertino, CA 95015 · last Feb 2, first Dec 6
Menlo Park, CA 94025 · last Feb 1, first Dec 7
Portola Valley, CA 94028 · last Feb 25, first Nov 25

Frequently asked questions

When is the last frost in Los Altos, CA?: For ZIP code 94023, the average last spring frost (32°F) is January 6, based on NOAA 1991-2020 climate normals for the Moffett Federal Airfield, CA weather station. There is a 1-in-10 chance of a frost after February 4.
When is the first frost in Los Altos, CA?: The average first fall frost (32°F) is December 23. There is a 1-in-10 chance of frost by December 3, so tender plants are at risk from that point on.
How long is the growing season in 94023?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 353 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.