You can experience different types of weather throughout the year at Rocky Mountain National Park. The winter months are from December to March. You will get to experience cold weather with deep snow at the higher elevations during this time. There could be seasonal closures of facilities and roads as well. The Spring months are April and May when the weather is unpredictable. The weather could be warm and sunny on a few days and cooler with heavy snow and rain on other days. Most of the trails are covered in snow during the Spring months. The summer season in this national park is between June and August when the weather is warm. You can expect a few thunderstorms, though. The Fall season is between September and November when the air is crisp with blue skies. You get to enjoy the fall colors and the elk rut if you visit the park during this time.