Winter (December through March) is brutally cold — −30°C is normal, −40°C not unusual — but it brings the aurora season, the trapline and snowmobile culture, and ice fishing. June to early September is the brief warm season, with long daylight, fishing, canoeing, and warm-water lakes; black flies and mosquitoes can be vicious in early summer.
September brings boreal autumn colour and a sweet spot of clear cold nights and reasonable daytime temperatures — arguably the most pleasant short window of the year. Spring breakup (April and May) is mud season; not recommended.