July is the best month. The weather is warm without being oppressive, the lake is fully swimmable, and the north woods are at their greenest. Long weekends in summer bring day-trippers up from Minneapolis, so the town gets busier than you might expect; if you want the lake to yourself, go mid-week.
Winter runs from December through March and is genuinely cold — temperatures of -20°C are not unusual, and some winters are worse. This is not a deterrent for locals, who embrace the season with ice fishing, snowmobiling, and cross-country skiing. The Polar Daze festival in late January is a deliberate celebration of the cold, featuring ice carvings, human bowling, and other events designed to get people outside when every instinct says to stay in.
Spring, from April through May, is unpredictable. Late snowfalls are common, the mud is considerable, and the lakes are only beginning to warm. Fall, from September through October, offers the best foliage in the north woods and notably smaller crowds. The colours peak in late September. Evenings get cold quickly; pack accordingly.