Ann Arbor, MI 48105 Frost Dates
When can you plant in Ann Arbor, MI?
Typically, the last spring freeze lands around 05/03, roughly 248 days out. The first fall frost typically arrives around 10/13, about 160 frost-free days later.
Ann Arbor sits in USDA Zone 6a (-10 to -5°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.
What to do before the first frost
About 7 weeks of growing season left in Ann Arbor before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/03 isn't a guarantee
05/03 is the middle of 30 years of NOAA records, not a promise. Plant by 04/20 and you're betting against frost in roughly 9 years out of 10. 05/20 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ann Arbor compares
Ann Arbor's growing season runs about 160 days, ranking 32,189 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 613 of 1,153.
Learn more
local microclimates covers what one yard in Ann Arbor can differ from the 48105 normal. zone vs. frost date covers why Zone 6a and Ann Arbor's frost date answer different questions.