The Kalahari is a semi-arid region with an average rainfall of 150mm in the southwest to 350mm in the northeast. The unreliable and irregular rains fall mostly during dramatic thunderstorms, often accompanied by strong winds and dust-storms, between November and April. The first rains transform the red dunes, covering them with the fresh yellow flowers of the dubbeltjie, Tribulus terrestris. Within two weeks fresh green grass begins to grow, but if the rains do not return, the vegetation will soon wither and the thirstland once again becomes apparent.

Temperatures vary greatly from -11°C on cold winter nights to 42°C in the shade on summer days when the ground surface temperature reaches a sizzling 70°C. During the winter months, when frost is common, the ground surface temperature can be 25°C lower that the temperature of the air. Winter in the Kalahari is a cool, dry season from September to October and then a hot, wet season from November to April.