That's one of the most frequently asked questions by people planning canoe trips. The long answer, however, goes into more detail.
Canoe tripping season starts as soon as lakes are free of ice.
Typically, large lakes like Opeongo and Cedar are impassable until the end of April. Smaller lakes and rivers open earlier. The two or three weeks after ice-out are a wonderful time to go on a canoe trip. If you don't mind the bugs, late May and early June canoe trips offer warm days, cool nights, reasonable water levels and the chance to have Algonquin Park pretty much to yourself. Visitors from the U.S. should note that the third weekend in May is a holiday weekend in Canada.