Lake Michigan's average high temperatures vary significantly by month, rising from the low 30s°F in winter (January/February) to the mid-70s-80s°F in summer (July/August), then cooling in fall, with peak warmth in July/August and coldest in January, reflecting typical Great Lakes seasonal patterns. For example, highs might be around 32°F in January, jump to 69°F in May, peak near 83°F in July, and fall to 60°F by October.
