South Tucson, AZ 85713 Frost Dates
85713, near South Tucson, AZ: the frost window
Around 01/20 is the usual last spring frost, about 145 days away. Fall's first freeze usually shows up around 12/17, roughly 332 days after the last spring frost.
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 South Tucson, not a forecast for this year.
Stretching the season past the first frost
South Tucson's growing season runs out in roughly 16 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around South Tucson's last frost
01/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/18 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/19 and only about 1 year in 10 sees frost after that.
South Tucson against the rest of the dataset
At roughly 332 frost-free days, South Tucson places 2,894 of 40,283 ZIP codes in this dataset. Within AZ, it ranks 153 of 506.
Learn more
Two guides worth reading on 85713: local microclimates, on what one yard in South Tucson can differ from the 85713 normal, and zone vs. frost date, on why Zone 9b and South Tucson's frost date answer different questions.