The forest by season
The forest is worth a trip in any season, and the spread in elevation means you can catch two at once, spring blooming in the lower draws while snow still holds on the high trails. Here is what each one brings.
Spring (April to May)
Spring works its way up the hills from the bottom. Pasqueflowers, the state flower, open on sunny slopes while patches of snow still linger, and by May the meadows fill in with prairie smoke, shooting stars, and wild iris. It is the quiet season, with active wildlife and waterfalls running full on snowmelt, Roughlock Falls in Spearfish Canyon among the best. Birds come back to the riparian corridors, and the dawn chorus peaks in late May. Lower routes like the Flume Trail near Sheridan Lake dry out first, while the high trails can stay snowbound and muddy into May, so check conditions and pack for rain or a late snow squall.
Summer (June to August)
Summer is peak season, with warm days and every trail open. The water pulls the crowds: Pactola Reservoir and Sheridan Lake for boating, swimming, and paddling, Deerfield Reservoir for quiet water and trout, and the mountain streams for fishing and cooling off. For wildlife, go early or late, when the heat backs off. Meadows along Deerfield Road and the reservoir margins are good bets for deer and elk at dusk, and beaver get busy in the evening. Afternoon thunderstorms are common in July and August, so start early. Base at a campground near the water; the where-to-stay guide compares the options, and forest offices can point kids toward Junior Forest Ranger activities.
Fall (September to October)
Fall is the one a lot of regulars wait for. After Labor Day the crowds thin, the air turns crisp, and the aspen, birch, and oak go gold and orange against the dark pines, best in Spearfish Canyon and along Deerfield Road from late September into the first week of October. The main event is the elk rut. From mid-September through October, bull elk bugle, a rising whistle that carries for miles in the still air, and dawn and dusk in the central meadows are the times to hear it. Keep at least 100 yards back; bulls are worked up and unpredictable during the rut.
Winter (November to March)
Snow changes the forest and thins it down to the people who want quiet. Fresh snow also turns the whole forest into a record of who went where. Tracks of deer, elk, turkey, and rabbit are everywhere, and with luck you will cut the line of a fox or a bobcat. Some animals stand out against the white: wild turkeys gather in bigger flocks along the roads, and bald eagles concentrate near open water below the dams, where fishing stays possible. Snowshoes or skis carry you into country like the Black Elk Wilderness with nothing but your own tracks behind you. Come ready for cold and short days, and know that many forest roads go unplowed.