Wind Cave National Park and the rest of the southern Black Hills are much warmer and drier than the northern hills. Some residents call the area South Dakota’s “banana belt.” The banana belt exists because of two weather patterns. The first weather pattern occurs when warm, moist air traveling east from the Pacific Ocean reaches the Rocky Mountains. The mountains force the air to rise, causing it to cool. When the air cools, the water vapor in the clouds condenses and falls as rain or snow. Once the air reaches the other side of the mountains, it is considerably drier. The dry air begins to descend, and becomes warmer again. The warm winds created by the descending air masses are called Chinook winds. This warm, dry air continues east and brings warmer and drier weather to the southern Black Hills.
Another weather pattern occurs when arctic air masses move south from Canada. When the frigid air masses encounter the summits of the northern Black Hills, they are deflected around the western and eastern slopes. Because Wind Cave National Park is located on the southern extremity of the hills, much of the cold air is funneled downward and away from the park and the southern hills.