When is the last frost in San Luis Obispo, CA?

For ZIP code 93409, the average last spring frost (32°F) is January 16, based on NOAA 1991-2020 climate normals for the San Luis Obispo Poly, CA weather station. There is a 1-in-10 chance of a frost after February 26.

When is the first frost in San Luis Obispo, CA?

The average first fall frost (32°F) is December 25. 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 93409?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 349 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 93409San Luis Obispo, CA

The average last spring frost in San Luis Obispo is January 16 and the average first fall frost is December 25, giving a typical growing season of about 349 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 16
Average first fall frost: Dec 25
Growing season: 349 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 9 · Feb 28 · Apr 12	Nov 5 · Dec 1 · Jan 4	276 days	99%
Frost / freeze (32°F)	Dec 11 · Jan 16 · Feb 26	Nov 25 · Dec 25 · Feb 12	349 days	68%
Hard freeze (28°F)	Dec 17 · Jan 9 · Feb 22	Dec 14 · Jan 6 · Feb 17	365 days	20%

Where these dates come from

ZIP code 93409 is matched to the NOAA station San Luis Obispo Poly, CA, 9.7 km away, at 308 ft elevation (82 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
San Luis Obispo Poly, CA (used)	308 ft	Jan 16	Dec 25
San Luis Obispo Ap, CA	200 ft	Jan 31	Dec 11
Pismo Beach, CA	39 ft	Feb 1	Jan 4
Morro Bay Fire Dept, CA	118 ft	Jan 19	Jan 14

Frost dates near San Luis Obispo

San Luis Obispo, CA 93401 · last Jan 16, first Dec 25
Pismo Beach, CA 93449 · last Jan 16, first Dec 25
Avila Beach, CA 93424 · last Feb 1, first Jan 4
Grover Beach, CA 93483 · last Feb 1, first Jan 4
Arroyo Grande, CA 93421 · last Feb 1, first Jan 4
Oceano, CA 93445 · last Feb 1, first Jan 4
Los Osos, CA 93412 · last Jan 19, first Jan 14
Nipomo, CA 93444 · last Feb 4, first Dec 13

Frequently asked questions

When is the last frost in San Luis Obispo, CA?: For ZIP code 93409, the average last spring frost (32°F) is January 16, based on NOAA 1991-2020 climate normals for the San Luis Obispo Poly, CA weather station. There is a 1-in-10 chance of a frost after February 26.
When is the first frost in San Luis Obispo, CA?: The average first fall frost (32°F) is December 25. 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 93409?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 349 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.