Parts of Australia will face catastrophic fire conditions on Friday, as heatwaves hit most of the country, creating the most significant conditions since the Black Summer bushfires.

Severe to extreme heatwaves have been declared in every state and territory in Australia, except for Queensland, with high temperatures forecast for days.

The state of Victoria has declared a total fire ban for Friday with northern areas shutting down 450 schools and childcare centres as well as parks, as the fire danger level for the region will be set at catastrophic - the highest level.

One meteorologist told the BBC that the combination of heatwaves and an elevated fire danger pose a risk not seen in years.

On Thursday, firefighters battled several fires in Victoria and New South Wales (NSW), with a dozen planes carrying water called in to tackle a large blaze near Wodonga city, according to the ABC.

Melbourne experienced its hottest day in six years on Wednesday with a high of 40.9°C (105.6°F), while some coastal towns in Western Australia hit 49°C.

In NSW, the heatwave is expected to peak on Saturday with Sydney facing a high of 42°C while areas of South Australia and Western Australia will see temperatures over 40°C in the coming days.

Friday will be the real peak of the current burst of heat, Angus Hines from the Bureau of Meteorology told the BBC.

It will be a very hot day for almost all of South Australia, Victoria, most of New South Wales, parts of Tasmania.

Wednesday marked the first significant heatwave for Melbourne and Adelaide, where millions of people live, and fire conditions are set to worsen on Friday, Hines added.

Firstly, the winds are strengthening across Victoria tomorrow, Hines said, noting that coupled with possible thunderstorms with little rain and dry lightning strikes, the fire danger will hit catastrophic levels for the northern parts of Victoria.

This event is being viewed as the most significant multi-day heatwave for inland southeast Australia since 2019-2020, the period of Australia's most severe fire season on record.

In Victoria, authorities on Thursday emphasized that a catastrophic fire danger rating means potential blazes can be unpredictable and uncontrollable.

Victoria's Emergency Management Commissioner Tim Wiebusch urged the community to prepare and act responsibly: Prepare now and enact your bushfire survival plan. If you are in an area of forecast catastrophic fire danger, leave early to an area with a lower fire risk.

Australia's fire danger ratings scale has four levels, with catastrophic being the highest level, followed by extreme, high and low.

A heatwave is declared when the minimum and maximum temperatures are expected to be unusually high for three days or more.