Grand Canyon combines geologic color and erosional forms in a canyon 277 river miles long, up to 18 miles wide, and a mile deep, overwhelming the senses through its immense size. The South Rim is open all year, while the North Rim is closed for the winter and will reopen on May 15, 2020, for the 2020 season. Weather in this region varies, with cold winters and mild pleasant summers, moderate humidity, and considerable diurnal temperature changes at higher elevations, while the bottom of the Grand Canyon has hotter, drier summers and cool damp winters. Summer thunderstorms and winter snowfall add to the weather variety.