When is the last frost in Superior, AZ?

For ZIP code 85173, the average last spring frost (32°F) is January 18, based on NOAA 1991-2020 climate normals for the Superior, AZ weather station. There is a 1-in-10 chance of a frost after March 1.

When is the first frost in Superior, AZ?

The average first fall frost (32°F) is December 28. There is a 1-in-10 chance of frost by December 1, so tender plants are at risk from that point on.

How long is the growing season in 85173?

In half of years, the frost-free season (between the last and first 32°F frost) is at least 342 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 85173Superior, AZ

The average last spring frost in Superior is January 18 and the average first fall frost is December 28, giving a typical growing season of about 342 days. Dates are based on NOAA 1991-2020 climate normals.

Average last spring frost: Jan 18
Average first fall frost: Dec 28
Growing season: 342 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 8 · Feb 18 · Mar 31	Nov 24 · Dec 11 · Jan 4	292 days	99%
Frost / freeze (32°F)	Dec 19 · Jan 18 · Mar 1	Dec 1 · Dec 28 · Feb 1	342 days	77%
Hard freeze (28°F)	Dec 22 · Jan 9 · Feb 10	Dec 14 · Jan 7 · Feb 5	365 days	26%

Where these dates come from

ZIP code 85173 is matched to the NOAA station Superior, AZ, 1.3 km away, at 2,860 ft elevation (15 ft higher than the ZIP code's center). Nearby stations for comparison:

Station	Elevation	Avg last frost	Avg first frost
Superior, AZ (used)	2,860 ft	Jan 18	Dec 28
Miami, AZ	3,560 ft	Feb 24	Dec 1
Globe #3, AZ	3,660 ft	Mar 11	Nov 21
Florence, AZ	1,400 ft	Jan 30	Dec 12

Frost dates near Superior

Apache Junction, AZ 85117 · last Feb 11, first Dec 10
Gold Canyon, AZ 85118 · last Feb 11, first Dec 10
Miami, AZ 85539 · last Feb 24, first Dec 1
Claypool, AZ 85532 · last Feb 24, first Dec 1
Kearny, AZ 85137 · last Mar 13, first Nov 19
Globe, AZ 85502 · last Feb 24, first Dec 1
Tortilla Flat, AZ 85190 · last Feb 11, first Dec 10
Roosevelt, AZ 85545 · last Jan 17, first Dec 25

Frequently asked questions

When is the last frost in Superior, AZ?: For ZIP code 85173, the average last spring frost (32°F) is January 18, based on NOAA 1991-2020 climate normals for the Superior, AZ weather station. There is a 1-in-10 chance of a frost after March 1.
When is the first frost in Superior, AZ?: The average first fall frost (32°F) is December 28. There is a 1-in-10 chance of frost by December 1, so tender plants are at risk from that point on.
How long is the growing season in 85173?: In half of years, the frost-free season (between the last and first 32°F frost) is at least 342 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.