Flagstaff, AZ 86015 Frost Dates
86015, near Flagstaff, AZ: the frost window
The last spring frost here typically falls around 06/21, about 297 days from today. Fall's first freeze usually shows up around 09/17, roughly 85 days after the last spring frost.
Flagstaff sits in USDA Zone 5b (-15 to -10°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
Flagstaff's growing season runs out in roughly 3 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
06/21 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 06/09 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 07/04 and only about 1 year in 10 sees frost after that.
Flagstaff against the rest of the dataset
At roughly 85 frost-free days, Flagstaff places 39,980 of 40,283 ZIP codes in this dataset. Within AZ, it ranks 505 of 506.
Learn more
Two guides worth reading on 86015: local microclimates, on what one yard in Flagstaff can differ from the 86015 normal, and zone vs. frost date, on why Zone 5b and Flagstaff's frost date answer different questions.