Winter rules Crater Lake National Park. It can start closing seasonal roads in mid-October and last through June. An average year sees 44 feet of snow dropped on the park. With that in mind, things can change dramatically from the quiet of winter to hustle and bustle of summer. Things To Know Before You Come - Crater Lake National Park (U.S. National Park Service) Mazama Campground is open late May through early October, weather permitting. Reservations can be made through the Lodge's website or toll-free phone number.