Phoenix, AZ 85020 Frost Dates
85020, near Phoenix, AZ: the frost window
Typically, the last spring freeze lands around 01/08, roughly 133 days out. Fall's first freeze usually shows up around 12/25, roughly 354 days after the last spring frost.
Phoenix sits in USDA Zone 10a (30 to 35°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Phoenix's growing season runs out in roughly 17 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
01/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 02/12 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 12/16 and only about 1 year in 10 sees frost after that.
Phoenix against the rest of the dataset
At roughly 354 frost-free days, Phoenix places 2,150 of 40,283 ZIP codes in this dataset. Within AZ, it ranks 38 of 506.
Learn more
Two guides worth reading on 85020: zone vs. frost date, on why Zone 10a and Phoenix's frost date answer different questions, and the frost range, on how to read the range around Phoenix's dates instead of trusting one.