Heat exhaustion can set in quickly during 40°C+ days. Keep water with you at all times. If you'd like more specifics, let me know: Which city or region are you visiting?
This is the longest day of the year. It is the moment when the Southern Hemisphere is tilted most directly toward the sun. While the Northern Hemisphere is shivering through the first day of winter, Australians are celebrating the "official" start of their summer.
Summer is peak fire season. Always check local fire danger ratings before traveling into rural areas.