The climate of Sydney is subtropical oceanic, with mild winters and warm summers. The wind blows frequently, especially from October to April, that is, in the warm season (being that it's in the Southern Hemisphere, the seasons in Sydney are reversed in comparison to Europe or North America).
In the warm half-year, from October to March, heatwaves may occur, with the wind blowing from the desert, which can raise the temperature above 35 °C (95 °F), though for short periods (sometimes, only one day); in addition, the wind can bring sand and dust from the desert.
Spring, from September to November, is mild or pleasantly warm, sunny enough, and generally not too rainy. Summer, from December to March, is warm, with average temperatures not too high, and generally pleasant: highs are on average about 25/26 °C (77/79 °F).
A copy of your important documents like your passport
Your Gallagher health insurance information
Change some US Dollars into Australian Dollars before you arrive or plan to use the airport ATM when you arrive. Take a card that doesn't charge international transaction fees.
One or more adapters and power converters for 230 volts (if your electronics are not already "dual voltage") - Australian outlets are different!
Click here for a general Pre-Departure Checklist for study abroad.