When is the last frost in Arroyo Grande, CA?

For ZIP code 93420, the average last spring frost (32°F) is February 4, based on NOAA 1991-2020 climate normals for the Twitchell Dam, CA weather station. There is a 1-in-10 chance of a frost after March 31.

When is the first frost in Arroyo Grande, CA?

The average first fall frost (32°F) is December 4. There is a 1-in-10 chance of frost by November 14, so tender plants are at risk from that point on.

How long is the growing season in 93420?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 301 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 93420Arroyo Grande, CA

The average last spring frost in Arroyo Grande is February 4 and the average first fall frost is December 4, giving a typical growing season of about 301 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Feb 4
Average first fall frost: Dec 4
Growing season: 301 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 14 · Mar 31 · Apr 26	Oct 21 · Nov 16 · Dec 6	231 days	100%
Frost / freeze (32°F)	Dec 27 · Feb 4 · Mar 31	Nov 14 · Dec 4 · Dec 28	301 days	98%
Hard freeze (28°F)	Dec 4 · Dec 31 · Feb 3	Nov 26 · Dec 17 · Jan 14	353 days	66%

Where these dates come from

ZIP code 93420 is matched to the NOAA station Twitchell Dam, CA, 23.7 km away, at 582 ft elevation (514 ft lower than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Twitchell Dam, CA (used)	582 ft	Feb 4	Dec 4
San Luis Obispo Ap, CA	200 ft	Jan 31	Dec 11
Pismo Beach, CA	39 ft	Feb 1	Jan 4
San Luis Obispo Poly, CA	308 ft	Jan 16	Dec 25

Frost dates near Arroyo Grande

Arroyo Grande, CA 93421 · last Feb 1, first Jan 4
Grover Beach, CA 93433 · last Feb 1, first Jan 4
Oceano, CA 93445 · last Feb 1, first Jan 4
Nipomo, CA 93444 · last Feb 4, first Dec 13
Pismo Beach, CA 93448 · last Feb 1, first Jan 4
San Luis Obispo, CA 93409 · last Jan 16, first Dec 25
Santa Maria, CA 93454 · last Feb 4, first Dec 13
Avila Beach, CA 93424 · last Feb 1, first Jan 4

Frequently asked questions

When is the last frost in Arroyo Grande, CA?: For ZIP code 93420, the average last spring frost (32°F) is February 4, based on NOAA 1991-2020 climate normals for the Twitchell Dam, CA weather station. There is a 1-in-10 chance of a frost after March 31.
When is the first frost in Arroyo Grande, CA?: The average first fall frost (32°F) is December 4. There is a 1-in-10 chance of frost by November 14, so tender plants are at risk from that point on.
How long is the growing season in 93420?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 301 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.