This map shows the average date of the last freeze in N. Lower and E. Upper Michigan. Some spots have an AVERAGE last freeze date in early June. The latest freeze ever in G.R. was June 4, 1945 (a crazy year when it reached the low 80s in March and then everything froze/frosted out).
Here’s the Mackinac Bridge – looking north – at 2:31 pm. Note the blue sky and the flag showing an east wind. Here’s some low temps. this AM (it was clear with calm winds in N. Lower MI and the U.P.): Low temps. this AM: 37 Kent City, 36 Big Rapids, 34 Baldwin, 32 Leota, 31 Cadillac, 30 Houghton Lake, 26 Grayling and Mio, 24 Alpena and Marquette, 21 Sawyer, 20 Atlanta and Kenton, 18 Doe Lake and Stonington, 17 Baraga Plains.