Tucson, AZ 85709 Frost Dates
Frost dates for Tucson, AZ, ZIP 85709
The last spring frost here typically falls around 01/20, about 145 days from today. The first fall frost typically arrives around 12/17, about 332 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 Tucson, not a forecast for this year.
What to do before the first frost
Zone 9b around Tucson has about 16 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.
Why 01/20 isn't a guarantee
01/20 is the middle of 30 years of NOAA records, not a promise. Plant by 02/18 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 Tucson compares
Tucson's growing season runs about 332 days, ranking 2,859 of 40,283 US ZIP codes measured here, longest to shortest. Within AZ, it ranks 150 of 506.
Learn more
local microclimates explains what one yard in Tucson can differ from the 85709 normal, and zone vs. frost date explains why Zone 9b and Tucson's frost date answer different questions.