Extending from the 10th to the 45th parallel, Australia has a remarkable variety of climates. The Tropic of Capricorn crosses it and 38% of its territory is found within the tropics: but the succession of climate from south to north corresponds to that which would be encountered on a voyage from Paris to the Gulf of Guinea. In fact, Tasmania has a climate not different from that of western France, while, with regard to temperature and rainfall, the climate of Darwin, in the Land of Arnhem, closely resembles that of Lagos in Nigeria. The configuration of the soil, on the other hand, contributes little to the variety of the climate: the continent is so flat that only 4% of the tropical area benefits significantly from its altitude, in the following small and separate regions:
But of these areas only the Atherton plateau, already mentioned, has a certain economic value. In the driest regions, no major settlement is possible, whatever the altitude. Another factor that contributes to the uniformity of the climate is the remarkable regularity of the coast, broken by only two gulfs, that of Carpentaria in the north and the large but flat southern gulf. As a result, the climate is much drier than that of, for example, Europe, where the Mediterranean penetrates right into the heart of the Ancient World. A third climatic factor is the great extension, surpassed only by that of North Africa, of the continent under the Tropic, that is to say the land area of greatest aridity: hence Australia is the driest land in the world, after the Sahara.
It is far enough from the equator to warn of the changing seasons. In the temperate region, July is the coldest month and January the hottest; summer occurs in the months of December, January and February, winter in the months of June, July and August. Such seasons are felt quite enough even in the sub-tropical zone and only along the northern coast are they replaced by seasons determined by the rains. This second type of climate extends from Broome to Darwin and Cairns. In Darwin the strong south-east trade winds cease in September and the air becomes very warm and calm: in December the rainy season begins, brought by the northwest monsoon, which last until March; calm and thunderstorms alternate until the end of April, when the coolest time of the year begins.
Temperature. – It is known that the southern hemisphere is somewhat colder than the northern one due to the greater southern oceanic spaces. But in the continental areas the temperatures are quite high; so along the 135th meridian; in Australia the average annual temperature is roughly the following:
According to Localcollegeexplorer, few regions of the world are actually as warm as northern Kimberley, where in fact in Wyndham the average annual temperature is 29 °, 2, a value surpassed only in the African lowlands on either side of Abyssinia. The average annual temperature across Australia is 21 °, 1: about the same as that of Cairo and New Orleans. Along the southern coast the average temperature is 15 °, 5 ° as in Northern Italy. Overall, the variation of the average temperature in relation to latitude is very regular, except for the north-western corner of the continent where an exceptionally hot area right on the tropic, in relation to an almost stable area of low pressure, has a temperature that rises up to 26 °, 6. Warm winds from the northwest are drawn to this area, making Nullagine and Marble Bar two of the hottest population centers in the world: at Marble Bar in the summer of 1921-22, the thermometer went up almost every day for three and a half months above 43 °! The coldest region of Australia is instead in the Australian Alps where there are two stations at about 1500 m. (Kiandra and Hôtel Kosciusko). Frosty days have been recorded for up to eight months in the southeastern highlands and are common throughout the interior of Australia in July; on the north and north-west coasts they have never been observed. The annual course of the temperature offers, for the succession of the seasons, very notable fluctuations that can be detected by the trend of the isotherms of the hottest and coldest months. The amplitude, between the averages of the extreme months, increases going from the coasts towards the indoor. The strips of the continent that extend into the southern waters have an amplitude of less than 8 °, 5 while in a central area, between Bourke and Marble Bar, the figure rises above 18 °. Almost the entire northern coast has an amplitude of less than 8 °, 5 with a minimum of 3 ° on the island Thursday.