On a day like today in Sydney they expect the temperatures to rise up to 38 degrees.
On your holidays the last thing you want is to get dehydrated and suffer a sunstroke.
How to stay cool and hydrated?
* Drink plenty of water (I know it will be hard while sitting in the sun at a bar and you want to cool your thirst with plenty of beers, do try to keep it to a minimum, as alcohol will make dehydration worse). Don't wait until you are really thirsty to drink. When you go out, just bring a bottle of water. There are many refill stations where you can top it up.
* Keep your body cool (wear loose/light colored clothes, eat fruit and salads, drink water, stay out of the sun, take cool showers/baths/swims)
* Keep your food safe (if you have food in your dorm room, see what would fit in the fridge, as the last thing you want to eat is molted bread or drink warm milk)
* Stay safe in the sun (wear sunscreen lotion (you should always do this in Australia), wear a hat and loose/light colored clothes and stay in the shade or go to places with airconditioning (cinemas/shopping malls)
* Warn others (especially when you are out with friends, make sure they also use sunscreen lotion (don't forget your back/top of your feet, your ears and eyelids)