When is the last frost in Norco, CA?

For ZIP code 92860, the average last spring frost (32°F) is January 17, based on NOAA 1991-2020 climate normals for the Chino Ap, CA weather station. There is a 1-in-10 chance of a frost after February 22.

When is the first frost in Norco, CA?

The average first fall frost (32°F) is December 19. There is a 1-in-10 chance of frost by November 27, so tender plants are at risk from that point on.

How long is the growing season in 92860?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 335 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 92860Norco, CA

The average last spring frost in Norco is January 17 and the average first fall frost is December 19, giving a typical growing season of about 335 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 17
Average first fall frost: Dec 19
Growing season: 335 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 21 · Feb 24 · Mar 29	Nov 12 · Dec 1 · Dec 18	278 days	100%
Frost / freeze (32°F)	Dec 18 · Jan 17 · Feb 22	Nov 27 · Dec 19 · Jan 17	335 days	85%
Hard freeze (28°F)	Dec 11 · Jan 3 · Jan 28	Dec 7 · Dec 30 · Jan 23	365 days	29%

Where these dates come from

ZIP code 92860 is matched to the NOAA station Chino Ap, CA, 9.6 km away, at 650 ft elevation (23 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Chino Ap, CA (used)	650 ft	Jan 17	Dec 19
Riverside Muni Ap, CA	805 ft	Jan 9	Dec 30
Ontario Intl Ap, CA	949 ft	Jan 4	Dec 30
Riverside Fire Stn 3, CA	840 ft	Jan 9	Dec 25

Frost dates near Norco

Corona, CA 92879 · last Jan 17, first Dec 19
Riverside, CA 92505 · last Jan 9, first Dec 30
Mira Loma, CA 91752 · last Jan 9, first Dec 30
Chino, CA 91708 · last Jan 17, first Dec 19
Ontario, CA 91761 · last Jan 17, first Dec 19
March Air Reserve Base, CA 92518 · last Jan 9, first Dec 25
Fontana, CA 92337 · last Jan 10, first Jan 2
Guasti, CA 91743 · last Jan 4, first Dec 30

Frequently asked questions

When is the last frost in Norco, CA?: For ZIP code 92860, the average last spring frost (32°F) is January 17, based on NOAA 1991-2020 climate normals for the Chino Ap, CA weather station. There is a 1-in-10 chance of a frost after February 22.
When is the first frost in Norco, CA?: The average first fall frost (32°F) is December 19. There is a 1-in-10 chance of frost by November 27, so tender plants are at risk from that point on.
How long is the growing season in 92860?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 335 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.