Why are Adelaide and Melbourne and Perth hotter than Brisbane and Sydney which seem to be further north?

Answer 1

Brisbane and Sydney, which are further north, are more influenced by northerly winds which bring humid conditions from the tropical and subtropical regions, accompanied by showers and thunderstorms. This moist weather usually occurs during the summer, resulting in lower temperatures. In addition, both Sydney and Brisbane lie to the east of the Great Dividing Range. Rain-bearing clouds from the east tend to stay on the eastern side of the range, cooling the temperatures of the cities found there.

Because the climate of Adelaide and Melbourne is characterised by dry summers and wet winters, unlike the north, this tends to result in long, hot, dry summers where the dry winds only serve to reinforce the excessive heat. These are the cities most likely to experience prolonged heatwaves. Perth is in the west, and apart from the "Fremantle Doctor", a strong wind that blows off the southwestern ocean, it is subject to the heat which is generated by the fact that most of the state of Western Australia is desert.