The Kimberley is located in the northern part of Western Australia, bordered on the west by the Indian Ocean, on the north by the Timor Sea, on the south by the Great Sandy Desert and Tanami Deserts, and on the east by the Northern Territory.
It covers an area of 423,517 square kilometres (163,521 sq mi), which is about three times the size of England or comparable to the size of California or 15% larger than Japan or twice the size of Victoria (Australia) or one sixth the size of Western Australia. It has a population of 38,000 estimated.
The Kimberley consists mainly of ancient, steep-sided mountain ranges from which the extreme climate has removed most soil except in the valleys of the Ord and Fitzroy Rivers in the southern part of the region. In these areas the soils are relatively usable cracking clays, whilst elsewhere they are LateriteOrthents. Although none of the mountains reach even 1,000 metres (3,281 ft), there is so much steep land as to make much of the region very difficult to traverse, especially during the wet season when even sealed roads are often flooded.
The Kimberley has a tropical monsoon climate. During the wet season, from November to April, the region receives about 90% of its rainfall, and cyclones are common especially around Broome. The annual rainfall, however, is highest in the northwest, where Kalumburu averages 1,270 millimetres (50 in) per year, and lowest in the southeast where it is around 520 millimetres (20 in). In the dry season, from May to October, south easterly breezes bring sunny days and cool nights. Climate change since 1967 has led to large increases of as much as 250 millimetres (10 in) per year in annual rainfall over the whole region. Recent studies suggest Asian air pollution and not global warming as the cause of this increased rainfall. In 1997 and 2000 the region received especially heavy rains, leading to record flooding of the Fitzroy and other rivers.
The Kimberley is the hottest part of Australia, with mean maxima almost always above 30 °C (86 °F) even in July and ranging in November before the rains break from 37 °C (99 °F) on the coast to 40 °C (104 °F) in the south around Halls Creek. Mean minima in July range from around 12 °C (54 °F) in the south to 16 °C (61 °F) around Kalumburu, whilst in November and December they are generally around 26 °C (79 °F).
The Kimberley is chiefly covered in open savanna woodland dominated by low eucalypt and Boab trees. In sheltered gorges of the high rainfall north, however, are patches of rainforest. These were not known to science until 1965. This wet area is one of the most floristically rich parts of Australia outside the Wet Tropics and southwestern WA.
