Flagstaff, AZ 86004 Frost Dates
Flagstaff, AZ: when does the frost end?
The last spring frost here typically falls around 05/13, about 258 days from today. Fall's first freeze usually shows up around 10/06, roughly 145 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Flagstaff in Zone 6b (-5 to 0°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 6 weeks until Flagstaff's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
05/13 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/27 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/30 and only about 1 year in 10 sees frost after that.
Flagstaff against the rest of the dataset
About 145 days separate Flagstaff's last and first frost, putting it 36,156 of 40,283 ZIP codes nationally. Within AZ, it ranks 476 of 506.
Learn more
Before leaning on 86004's figures: zone vs. frost date explains why Zone 6b and Flagstaff's frost date answer different questions, while the frost range explains how to read the range around Flagstaff's dates instead of trusting one.