The Nullarbor Plain is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its north. It is the world’s largest single exposure of limestone bedrock, and occupies an area of about 200,000 square kilometres. At its widest point, it stretches about 1,100 kilometres from east to west across the border between South Australia and Western Australia.
The Nullarbor has a desert climate, with arid to semi-arid conditions. Inland, summers can be scorching hot, with daytime temperatures close to 50 °C while in winter nights can drop well below freezing. Closer to the coast, the temperature is milder with more rainfall in the winter months. The mean annual rainfall at Cook is 184.1 millimetres with most rain falling between May and August. Summers are very dry, with rain falling mainly from sporadic storms; however, occasionally decaying tropical systems can cause heavier rain in the summer months. Temperatures on the plain have ranged from 49.9 °C at the like-named Nullarbor, South Australia which is the fourth hottest recorded temperature (and the hottest recorded December temperature) in all of Australia, to −7.2 °C at Eyre, which is the coldest recorded temperature in Western Australia.