Karijini National Park, at 627,442 hectares is the second largest national park in Western Australia, centred in the Hamersley Ranges of the Pilbara region. Situated just north of the Tropic of Capricorn, the park's climate can best be described as tropical semi-arid desert. A highly variable, mainly summer rainfall of 250–350 mm, often associated with thunderstorms and cyclones, is accompanied by temperatures frequently topping 40 degrees Celsius. The dominant flora of the Pilbara is acacia trees and shrubs and drought-resistant Triodia spinifex grasses.