When is the last frost in Palo Alto, CA?

For ZIP code 94309, the average last spring frost (32°F) is February 1, based on NOAA 1991-2020 climate normals for the Palo Alto, CA weather station. There is a 1-in-10 chance of a frost after March 4.

When is the first frost in Palo Alto, CA?

The average first fall frost (32°F) is December 7. There is a 1-in-10 chance of frost by November 20, so tender plants are at risk from that point on.

How long is the growing season in 94309?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 310 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 94309Palo Alto, CA

The average last spring frost in Palo Alto is February 1 and the average first fall frost is December 7, giving a typical growing season of about 310 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Feb 1
Average first fall frost: Dec 7
Growing season: 310 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 5 · Mar 11 · Apr 15	Nov 3 · Nov 21 · Dec 8	252 days	100%
Frost / freeze (32°F)	Dec 28 · Feb 1 · Mar 4	Nov 20 · Dec 7 · Jan 6	310 days	96%
Hard freeze (28°F)	Dec 15 · Jan 4 · Feb 17	Dec 3 · Dec 22 · Jan 25	358 days	60%

Where these dates come from

ZIP code 94309 is matched to the NOAA station Palo Alto, CA, 0.3 km away, at 25 ft elevation (5 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Palo Alto, CA (used)	25 ft	Feb 1	Dec 7
Redwood City, CA	31 ft	Jan 17	Dec 12
Moffett Federal Airfield, CA	39 ft	Jan 6	Dec 23
Woodside Fire Stn 1, CA	380 ft	Feb 25	Nov 25

Frost dates near Palo Alto

Palo Alto, CA 94302 · last Feb 1, first Dec 7
Stanford, CA 94305 · last Feb 1, first Dec 7
Menlo Park, CA 94025 · last Feb 1, first Dec 7
Atherton, CA 94027 · last Jan 17, first Dec 12
Los Altos, CA 94023 · last Jan 6, first Dec 23
Mountain View, CA 94043 · last Jan 6, first Dec 23
Redwood City, CA 94063 · last Jan 17, first Dec 12
Portola Valley, CA 94028 · last Feb 25, first Nov 25

Frequently asked questions

When is the last frost in Palo Alto, CA?: For ZIP code 94309, the average last spring frost (32°F) is February 1, based on NOAA 1991-2020 climate normals for the Palo Alto, CA weather station. There is a 1-in-10 chance of a frost after March 4.
When is the first frost in Palo Alto, CA?: The average first fall frost (32°F) is December 7. There is a 1-in-10 chance of frost by November 20, so tender plants are at risk from that point on.
How long is the growing season in 94309?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 310 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.