WHY DOES IT RAIN IN PERTH AT WINTER WITH LOW TEMPERATURES?
The prevailing wind across southern Australia in winter is a westerly. In the summer, it is an easterly. Westerly winds come off the Indian Ocean in to Perth bringing moist air that rises and produces cloud and rain. Easterly winds in summer come off the dry inland and produce no rain. In Sydney, the same easterlies in summer are off the Tasman Sea and bring moisture, cloud and rain while in winter, the westerlies are off the land and are dry. Sydney gets most of its severe thunderstorms in summer while Perth gets most of its severe storms in winter because that is when the moisture is available. The same westerly winds bring a winter maximum rainfall to Adelaide and Melbourne while the easterlies bring summer maximum rainfalls to the whole east coast north of Sydney including Brisbane.
