Australia Blaze Crisis

At least one home has been destroyed and more are expected to be lost as firefighters face days of battling a massive blaze in western Victoria.

Tens of thousands of residents from communities near Ballarat were told to "leave immediately" as the bushfire, which began at Bayindeen, accelerated and ultimately ripped through more than 11,000 hectares.

About 1,000 firefighters, hundreds of trucks and almost 60 aircraft — including four large air tankers — have been battling the blaze, with investigators yet to determine the cause.

Impact assessment teams started to assess the scale of the fire's destruction.

A wind change had the bushfire shift direction from southeasterly to northeasterly.

Winds reached about 69 km/h but were expected to stay at about 30 km/h for the remainder of the day.

More than 25,000 homes were sent emergency alerts through voice or text messages and about 5500 more went out. Premier Jacinta Allan said it was a tough night for residents west of Ballarat.

The very large bushfire forced the closure of the train line between Ballarat and Ararat, which authorities hoped to reopen.

Emergency warnings, a watch and act and advice alerts remained in place for several communities north of Beaufort as the bushfire headed towards the Elmhurst and Amphitheatre region.

A high fire danger alert has also been issued for parts of central and southwestern NSW, in addition to the Greater Hunter region.

Hot conditions were likely to be focused on Northern and Eastern NSW, Bureau of Meteorology meteorologist Dean Narramore said.

The mercury was set to reach the mid to high 30s in Sydney before widespread thunderstorm activity and a cool change in the evening.

A bushfire watch and act alert is in place for people traveling along the Eyre Highway near the Balladonia Roadhouse in parts of Balladonia and the Fraser Range in the Shire of Dundas.