When is the last frost in San Manuel, AZ?

For ZIP code 85631, the average last spring frost (32°F) is February 4, based on NOAA 1991-2020 climate normals for the San Manuel, AZ weather station. There is a 1-in-10 chance of a frost after March 2.

When is the first frost in San Manuel, AZ?

The average first fall frost (32°F) is December 8. 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 85631?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 306 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 85631San Manuel, AZ

The average last spring frost in San Manuel is February 4 and the average first fall frost is December 8, giving a typical growing season of about 306 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Feb 4
Average first fall frost: Dec 8
Growing season: 306 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 2 · Mar 1 · Mar 30	Nov 9 · Nov 25 · Dec 11	268 days	100%
Frost / freeze (32°F)	Jan 5 · Feb 4 · Mar 2	Nov 20 · Dec 8 · Dec 28	306 days	100%
Hard freeze (28°F)	Dec 17 · Jan 10 · Feb 11	Dec 3 · Dec 22 · Jan 25	346 days	78%

Where these dates come from

ZIP code 85631 is matched to the NOAA station San Manuel, AZ, 3.5 km away, at 3,420 ft elevation (451 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
San Manuel, AZ (used)	3,420 ft	Feb 4	Dec 8
Oracle Sp, AZ	4,595 ft	Mar 29	Nov 13
Oracle 2 Se, AZ	4,510 ft	Mar 23	Nov 22
Mt Lemmon Willow Canyon, AZ	7,027 ft	Apr 1	Nov 19

Frost dates near San Manuel

Mammoth, AZ 85618 · last Mar 13, first Nov 19
Oracle, AZ 85623 · last Mar 23, first Nov 22
Mount Lemmon, AZ 85619 · last Mar 23, first Nov 22
Tucson, AZ 85739 · last Apr 2, first Nov 11
Catalina, AZ 85738 · last Apr 2, first Nov 11
Winkelman, AZ 85192 · last Mar 13, first Nov 19
Hayden, AZ 85135 · last Mar 13, first Nov 19
Cortaro, AZ 85652 · last Feb 11, first Dec 2

Frequently asked questions

When is the last frost in San Manuel, AZ?: For ZIP code 85631, the average last spring frost (32°F) is February 4, based on NOAA 1991-2020 climate normals for the San Manuel, AZ weather station. There is a 1-in-10 chance of a frost after March 2.
When is the first frost in San Manuel, AZ?: The average first fall frost (32°F) is December 8. 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 85631?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 306 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.