National Weather Service United States Department of Commerce

Fog will be possible again tonight for some, especially across the eastern UP and adjacent to the Lake Michigan shoreline. Following a dry end to the weekend and start to the week, the chance for showers and thunderstorms returns on Tuesday. Expect humidity to steadily build through the middle of the week as temperatures climb into the 80s and lower 90s.
Sunday will feature mostly sunny skies and warm temperatures in the 70s and 80s as high pressure sticks around. However, even though the risk for dangerous waves or currents is low, lake temperatures are still cold—hovering in the 50s—which means swimmers face a real risk of hypothermia.
Heat and humidity will steadily build throughout the week, peaking mid to late week. Although scattered showers and thunderstorms could slightly alter the exact high temperatures, the heat will still pose a significant risk—especially to sensitive groups and those without adequate hydration.