Superior, AZ 85173 Frost Dates
When can you plant in Superior, AZ?
The last spring frost here typically falls around 01/18, about 143 days from today. The first fall frost typically arrives around 12/28, about 342 frost-free days later.
Zone 9b (25 to 30°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Superior, not a forecast for this year.
What to do before the first frost
About 17 weeks of growing season left in Superior before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 01/18 isn't a guarantee
01/18 is the middle of 30 years of NOAA records, not a promise. Plant by 03/01 and you're betting against frost in roughly 9 years out of 10. 12/19 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Superior compares
About 342 days separate Superior's last and first frost, putting it 2,557 of 40,283 ZIP codes nationally. Within AZ, it ranks 140 of 506.
Learn more
local microclimates covers what one yard in Superior can differ from the 85173 normal. zone vs. frost date covers why Zone 9b and Superior's frost date answer different questions.