Like the rest of the state, southwestern Colorado is intensely seasonal. Snow typically begins falling in the high country in late September or early October, and by Halloween seasonal closures turn some unpaved alpine roads into routes for snowmobiles. The San Juan Mountains see average annual snowfalls approaching 400 inches in the highest spots. Winter lingers well into the season that is called spring on the calendar—the greatest snowfalls generally occur in March and April.
Skiing winds down in early to mid-April, as the snow in the higher elevations begins to melt. Cresting streams provide thrilling, if chilling, white-water rafting and kayaking. Hiking and biking trails become accessible, and wildflowers begin their short, intense season of show. Summer is glorious in the mountains, with brilliant sunshine and cobalt-blue skies. Late summer brings brief and often intense showers on many an afternoon, sometimes accompanied by dramatic thunder and lightning. Summer tourism winds down after Labor Day and, in some areas, shuts down completely in October. The mountains are popular year-round, but spring and fall are the best times to visit the hot, dry climate of the Mesa Country around the Four Corners.