Maricopa, AZ 85139 Frost Dates
85139, near Maricopa, AZ: the frost window
Typically, the last spring freeze lands around 02/23, roughly 179 days out. Fall's first freeze usually shows up around 11/24, roughly 274 days after the last spring frost.
Maricopa sits in USDA Zone 9a (20 to 25°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
Maricopa's growing season runs out in roughly 13 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 02/23 isn't a guarantee
02/23 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 01/29 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 03/15 and only about 1 year in 10 sees frost after that.
Maricopa against the rest of the dataset
About 274 days separate Maricopa's last and first frost, putting it 5,143 of 40,283 ZIP codes nationally. Within AZ, it ranks 305 of 506.
Learn more
Two guides worth reading on 85139: local microclimates, on what one yard in Maricopa can differ from the 85139 normal, and zone vs. frost date, on why Zone 9a and Maricopa's frost date answer different questions.