If wildlife is your priority, aim for May–June or September–early October. Late spring gives you the easiest bear viewing of the year, with bears feeding low in the valley and newborn elk calves in the meadows. Early fall brings the elk rut — bulls bugling and clashing antlers — plus bears fattening up on berries before winter. Both windows pair active wildlife with fewer crowds than peak summer.
Whatever month you pick, go at dawn or dusk: animals are most active just after sunrise and around sunset, while midday is the quietest stretch. Summer has the longest days and lots of young animals but the biggest crowds, and winter trades variety for snowy scenery and roadside sheep and deer. The locals' tip: September is the most underrated month — rut, larches and lower rates all at once.