People have been advised to avoid non-essential travel and many have been working from home.
Some schools have closed early, or chosen not to open at all, while the extreme heat is putting pressure on the health service.
But countries where temperatures are usually higher have adapted their infrastructure and lifestyle to cope with the heat.
There is no extreme temperature threshold that forces Australian schools to shut. For some students, this knowledge can really melt your icy pole [ice lolly].
Instead, schools aim to keep students as safe and comfortable as possible. Policies vary between states. Many classrooms have air conditioning but others rely on a patchwork of measures.
These include using fans, altering uniform rules, creating spaces with better ventilation, and encouraging students to bring water bottles. Outside, students are advised to seek shade.
PE classes should be avoided in the middle of the day, officials say. New South Wales, for instance, suggests "scheduling sport in the mornings and swimming carnivals in the evenings" as examples of alternative approaches.
Staff are urged to watch for signs of heat stress. Parents can apply sunscreen to children before school and make sure they have a hat, according to advice notices.
It is a different story, of course, if a school is under threat from bushfire. Hundreds of campuses were closed during Australia's Black Summer blazes in 2019-20.