The best months to visit Theodore Roosevelt National Park in North Dakota are June and September. June offers the "greenest" version of the Badlands, with vibrant wildflowers and high wildlife activity, including the birth of bison calves (red dogs). September is equally spectacular, featuring crisp, comfortable temperatures for hiking and the onset of fall colors in the cottonwood trees along the Little Missouri River. While July and August are popular for the warm weather, they can be uncomfortably hot, with temperatures often exceeding 90∘F and occasional severe thunderstorms. If you are a birdwatcher, late May is ideal for catching migratory species. For those who prefer solitude and don't mind the cold, October provides a quiet atmosphere before the harsh winter sets in. Winter (December–March) is beautiful but challenging, with many park roads and facilities closed due to snow, though it offers unique opportunities for cross-country skiing and seeing the bison against a stark, white landscape.