Reference Material and Books The Alaska Natural History Association is a good source for books, maps, and field guides about Alaska's natural and cultural history. When to visit Mountain weather is unpredictable. Throughout our operating season, from early June through early September, temperatures can vary from lows around freezing to highs in the mid 80s. We experience warm, sunny days when shorts, t-shirt, and a dip in Nugget Pond are in order, and wet, blustery periods when you'll want to curl up with a book next to a warm fire. We have known Mount McKinley to stay hidden for nine consecutive days and have had the massif in full view for three straight weeks. We have seen snow every month of summer, yet have sunbathed in May and September.