During the spring, the mountains in the forest are covered with a thick blanket of snow. As summer rolls around the high elevations may still hold snowfields however you will also see.wildflowers as well. During temperatures that are 70 and above monsoons develop and bring thunderstorms. As summer turns to autumn the aspen trees begin to turn golden then the temperature begins to chill and fall turns to winter. The San Juan Mountains are popular because of their deep snow that averages 460 inches a year.