Birmingham, MI 48009 Frost Dates
48009, near Birmingham, MI: the frost window
Typically, the last spring freeze lands around 05/01, roughly 246 days out. Fall's first freeze usually shows up around 10/17, roughly 165 days after the last spring frost.
Birmingham sits in USDA Zone 6b (-5 to 0°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
Birmingham's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 05/01 isn't a guarantee
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/19 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/16 and only about 1 year in 10 sees frost after that.
Birmingham against the rest of the dataset
At roughly 165 frost-free days, Birmingham places 30,511 of 40,283 ZIP codes in this dataset. Within MI, it ranks 439 of 1,153.
Learn more
Two guides worth reading on 48009: zone vs. frost date, on why Zone 6b and Birmingham's frost date answer different questions, and the frost range, on how to read the range around Birmingham's dates instead of trusting one.