When is the last frost in Bethel Island, CA?

For ZIP code 94511, the average last spring frost (32°F) is January 12, based on NOAA 1991-2020 climate normals for the Antioch Pumping Plt #3, CA weather station. There is a 1-in-10 chance of a frost after February 1.

When is the first frost in Bethel Island, CA?

The average first fall frost (32°F) is December 19. There is a 1-in-10 chance of frost by November 29, so tender plants are at risk from that point on.

How long is the growing season in 94511?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 343 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 94511Bethel Island, CA

The average last spring frost in Bethel Island is January 12 and the average first fall frost is December 19, giving a typical growing season of about 343 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 12
Average first fall frost: Dec 19
Growing season: 343 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 11 · Feb 8 · Mar 12	Nov 18 · Dec 4 · Dec 28	299 days	100%
Frost / freeze (32°F)	Dec 20 · Jan 12 · Feb 1	Nov 29 · Dec 19 · Jan 12	343 days	81%
Hard freeze (28°F)	Dec 16 · Jan 2 · Jan 22	Dec 9 · Dec 29 · Jan 16	365 days	35%

Where these dates come from

ZIP code 94511 is matched to the NOAA station Antioch Pumping Plt #3, CA, 10.8 km away, at 60 ft elevation (67 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Antioch Pumping Plt #3, CA (used)	60 ft	Jan 12	Dec 19
Tracy Pumping Plt, CA	61 ft	Jan 19	Dec 10
Stockton Fire Stn 4, CA	12 ft	Feb 5	Dec 8
Mt Diablo Junction, CA	2,170 ft	Mar 8	Dec 22

Frost dates near Bethel Island

Knightsen, CA 94548 · last Jan 12, first Dec 19
Oakley, CA 94561 · last Jan 12, first Dec 19
Brentwood, CA 94513 · last Jan 12, first Dec 19
Antioch, CA 94531 · last Jan 12, first Dec 19
Discovery Bay, CA 94505 · last Jan 19, first Dec 10
Isleton, CA 95641 · last Jan 12, first Dec 19
Rio Vista, CA 94571 · last Jan 12, first Dec 19
Stockton, CA 95208 · last Feb 5, first Dec 8

Frequently asked questions

When is the last frost in Bethel Island, CA?: For ZIP code 94511, the average last spring frost (32°F) is January 12, based on NOAA 1991-2020 climate normals for the Antioch Pumping Plt #3, CA weather station. There is a 1-in-10 chance of a frost after February 1.
When is the first frost in Bethel Island, CA?: The average first fall frost (32°F) is December 19. There is a 1-in-10 chance of frost by November 29, so tender plants are at risk from that point on.
How long is the growing season in 94511?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 343 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.