Phoenix, AZ 85023 Frost Dates
Frost dates for Phoenix, AZ, ZIP 85023
Around 01/08 is the usual last spring frost, about 133 days away. The first fall frost typically arrives around 12/25, about 354 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 Phoenix, not a forecast for this year.
What to do before the first frost
Zone 9b around Phoenix has about 17 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
How much risk comes with planting early here
01/08 is the middle of 30 years of NOAA records, not a promise. Plant by 02/12 and you're betting against frost in roughly 9 years out of 10. 12/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Phoenix compares
At roughly 354 frost-free days, Phoenix places 2,153 of 40,283 ZIP codes in this dataset. Within AZ, it ranks 41 of 506.
Learn more
local microclimates explains what one yard in Phoenix can differ from the 85023 normal, and zone vs. frost date explains why Zone 9b and Phoenix's frost date answer different questions.