Ann Arbor, MI 48113 Frost Dates
48113, near Ann Arbor, MI: the frost window
Typically, the last spring freeze lands around 05/08, roughly 253 days out. Fall's first freeze usually shows up around 10/04, roughly 147 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Ann Arbor in Zone 6a (-10 to -5°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
Ann Arbor's growing season runs out in roughly 5 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 Ann Arbor's last frost
05/08 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/23 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/26 and only about 1 year in 10 sees frost after that.
Ann Arbor against the rest of the dataset
Ann Arbor's growing season runs about 147 days, ranking 35,827 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 857 of 1,153.
Learn more
Two guides worth reading on 48113: local microclimates, on what one yard in Ann Arbor can differ from the 48113 normal, and zone vs. frost date, on why Zone 6a and Ann Arbor's frost date answer different questions.