Extreme and severe heatwave warnings are forecast for Western Australia, South Australia, Victoria and Tasmania this week .
Temperatures in South Australia and Western Australia have nudged over 40 degrees, with some towns forecast to keep climbing until mid-week.
The heatwave will move along the south coast of the country, with severe weather hitting Melbourne and Hobart by the weekend.
The early week forecast has an extreme heatwave passing over south-east Western Australia and south-west South Australia.
The Bureau of Meteorology has issued a severe heatwave warning for surrounding areas, including central Western Australia and across the South Australian border.
The low-intensity heatwave stretches from mid-coast Western Australia across to western Queensland, NSW and Victoria, spanning much of the country.
The hot weather will roll along the southern coast of Australia, with the extreme heatwave cooling into a severe warning mid week.
IN OTHER NEWS:
The heatwave will move through South Australia into Victoria and Tasmania towards the end of the week.
South Australia is forecast to have a widespread low-intensity heatwave across most of state by Thursday, with severe heatwaves covering the coastline and edging towards Melbourne.
The weekend's forecast predicts severe to low-intensity heatwaves in Tasmania and southern Victoria.