It’s difficult to make any generalizations about Michigan’s climate, given that its two peninsulas cover a lot of latitude, and the Great Lakes tend to complicate weather patterns. Still, the state’s weather is probably more moderate than you think, since the ever-looming Great Lakes cool the hot summer air and warm the cold winter winds.
Michigan has four distinct seasons. Summers require shorts and T-shirts almost everywhere (except near Lake Superior, where you’ll want a sweatshirt handy). July and August temperatures average in the 80s in the Lower Peninsula and the 70s in the Upper Peninsula. Come December through February, they drop to the 30s in the L.P. and the 20s in the U.P. (Temperatures listed here are in degrees Fahrenheit.)
But don’t take any of this too seriously. You can enjoy springlike skiing conditions in the U.P. in February, or freeze to death at Thanksgiving. You may swelter on a summer hike through the woods, then grab for your fleece on a Great Lakes beach. Michigan is anything but predictable.
The Lake Effect
The Great Lakes act like insulators—slow to warm up, slow to cool down. That’s what allows for Michigan’s valuable fruit harvest: Lake Michigan moderates springtime temperatures, so fruit trees and vines aren’t usually tempted to bud until the threat of frost has passed.
The Great Lakes also have a dramatic effect on snowfall. Dry winter air travels over the Great Lakes on the prevailing western winds, absorbing moisture. When this air hits land, it dumps its load of precipitation in the form of snow. Weather people refer to this phenomenon as lake effect snows, which can be surprisingly localized—hence, the reason you’ll find many of Michigan’s ski resorts clustered along the western edge of the state.
The prevailing western breezes also affect water temperatures, most noticeably on Lake Michigan. In summer, the warm surface waters tend to blow right into those nice, sandy beaches along the lake’s eastern edge. While Lake Michigan is rarely warm enough for swimming on the Wisconsin side, it can be downright pleasant in Michigan—as evidenced by the numerous popular beaches lining the state.
Lake Superior is another story. Temperatures on this deep, huge, northern lake never climb out of the 40s, save for the occasional shallow bay. “No one’s ever drowned in Lake Superior,” the saying goes. “They all die of hypothermia first.”
Freshwater freezes faster than saltwater, and the Great Lakes will often freeze over from land to several miles out. The ice gets thick enough for brave souls to snowmobile to the islands, especially nearby ones like Mackinac. The commercial shipping season shuts down from mid-January to late March, but bad weather often hampers it for much longer. Commercial ships regularly pound through ice up to a foot thick; more than that, and they rely on the Coast Guard’s new Mackinaw, a 240-foot reinforced ship designed for ramming a passage through ice.
You can usually count on snow and cold temperatures in northern Michigan from Thanksgiving to Easter. If you want reliable snow, head to the Upper Peninsula. While the Detroit area averages about 41 inches of snow a year, the U.P. gets blanketed with more than 160 inches annually.
U.P. snows are legendary, especially in the Keweenaw Peninsula, where 300-inch winters aren’t that unusual. (Sticking far out into Lake Superior, it really gets nailed with lake effect snows.) In summer, you’ll often notice curious elevated, pierlike contraptions leading from some houses to the sidewalk—no need to shovel those front walks in winter until there’s at least 24 inches on the ground. Ladders nailed to roofs are there for a reason, too. When accumulated snows threaten to collapse the roof, the ladders give a foothold from which to clear off the stuff.
You should be aware of a dangerous little thing called the windchill factor, when cold temperatures are coupled with biting winds. If it’s 5°F outside, a 15-mph wind will make it feel like -25°. Besides being exceedingly uncomfortable, it means you’re at an even greater risk for frostbite or hypothermia. Weather forecasts tend to warn you about the windchill factor, but not always; remember to consider both the temperature and the wind speed when dressing for the outdoors.
That said, many people welcome Michigan’s winter, which constitutes a huge piece of the state’s tourism pie. Few other areas in the Midwest can offer as reliable a season for skiing, snowboarding, snowmobiling, ice fishing, and snowshoeing. Of course, sitting around a fire or soaking in a hot tub is acceptable behavior, too.
by Laura Martone from Moon Michigan, 3rd Edition, © Avalon Travel