Island in the Sea of Grass
The Black Hills are sometimes described as an island rising within a sea of grass. This sudden rise in elevation and the resulting slopes and exposures produce a much different climate than the surrounding plains. Wind Cave National Park lies on the southern tip of the "island" and, like the rest of the southern hills, has weather patterns that are greatly influenced by the Rocky Mountains to the west and the higher peaks of the northern Black Hills. Generally, the climate is semi-arid with mild winters and warm summers.
What a Difference
Climate and weather are not the same! Climate is a general term used to express broad patterns - for example, South Dakota's climate is sunny with warm summers and cold winters. Weather applies to specific movements of air masses, levels of precipitation, and temperature fluctuations at specific times of year--for example, today's weather is partly cloudy.
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.
Listen to the prairie thunderstorm (84k wma file)
Monthly Weather Summary