Victorians are set for sweltering conditions over the coming week with temperatures to surpass 40 degrees in many parts of the state.

Victorians are set for sweltering conditions over the coming week with temperatures to surpass 40 degrees in many parts of the state.

Millions will swelter over the Australia Day long weekend, with forecasts of extreme heatwave temperatures, while a cyclone is headed for one state.

Temperatures are expected to reach the mid-40s in some towns and cities on Australia as southern states swelter through a record-breaking heatwave.

Temperatures are expected to reach the mid-40s in some towns and cities on Australia as southern states swelter through a record-breaking heatwave.

Melbourne is forecast to swelter through a maximum 45 degrees on Tuesday, but a cool change at night will send temperatures plummeting.

Melbourne is forecast to swelter through a maximum 45 degrees on Tuesday, but a cool change at night will send temperatures plummeting.

Melbourne is forecast to swelter through a maximum 45 degrees on Tuesday, but a cool change at night will send temperatures plummeting.

A dangerously hot long weekend forecast for Victoria this weekend has fire authorities on high alert.

A dangerously hot long weekend forecast for Victoria this weekend has fire authorities on high alert.