The best time to visit Alamosa, Colorado, is during the summer months, from June to August, and the shoulder seasons of late spring (May) and early fall (September).Summer offers the most pleasant weather for exploring the Great Sand Dunes National Park and Preserve, with warm days superb for hiking, sandboarding, and stargazing. While daytime temperatures can reach the 80s°F (27-32°C), evenings cool down considerably, making it comfortable for outdoor activities. This is an ideal time for families looking to enjoy nature and outdoor adventures.For those preferring fewer crowds and mild temperatures, late spring and early fall are excellent choices. May brings wildflowers and comfortable hiking weather, while September offers crisp air and golden aspen foliage in the surrounding mountains.