The Great Smoky Mountains National Park, and the surrounding areas, feature elevations that range from 800 feet to over 6,640 feet. This drastic change in altitude can affect weather in unpredictable ways. Temperatures in upper elevations are normally ten to twenty degrees cooler than that of the valley. Rainfall averages 55 inches per year in the low-lands to 85 inches per year at Clingmans Dome. With this in mind, it is always suggested to be prepared when hiking, camping or exposing yourself to the elements at higher altitudes. Spring in the mountains is often unpredictable, so dress in layers when going out and take cold weather clothing. Summer is hot and humid, but far more pleasant in the higher elevations. Remember to never drink from streams when hot, no matter how fresh or clear it might appear. Fall brings warm days and cool nights. Light snow can occur in the mountains, so dress warm when viewing the fabulous fall foliage. Winter is relatively mild in the Smokies, but with increasing elevations comes a greater chance of snow. Though it may seem warm and comfortable in the valley, be cautious of sudden snowfall in higher elevations and be prepared.