An extreme heat warning has been issued for Victoria, with temperatures expected to exceed 40 degrees Celsius in some parts of the state.

In the north-west, Mildura and Swan Hill are expecting tops of 42C, while in the north, Echuca and Albury-Wodonga are both heading for 41C.

Melbourne is expected to reach a top of 34C.

Victoria’s Chief Health Officer, Professor Charles Guest, said the warning applied across all of Victoria’s northern districts, but people in Melbourne and other parts of the state should also take care.

“It would be wise for everyone across the state to keep drinking water, to avoid leaving children, animals, old people in cars, that’s a very dangerous practice,” he said.

“Of course, stay cool, keep out of the sun.”

Conditions would also be hot on Monday in Sydney (32C), Brisbane (31C), Adelaide (33C), Canberra (39C) and Darwin (33C).

Just outside the ACT, a top of 40C is forecast for Yass.

It will also be hot on the NSW south coast, with 38C forecast for Batemans Bay.

The ACT Ambulance Service has warned Canberrans to avoid heat stress by taking sensible precautions.

This includes drinking plenty of water, avoiding strenuous exercise during the hottest parts of the day, and not leaving children or pets in cars.

A total fire ban has also been declared in the Southern Slopes, Southern Ranges and Monaro Alpine regions of New South Wales.

A total fire ban has been declared across Victoria today for the first time this summer, with the Country Fire Authority expecting conditions to be the worst experienced so far.

The CFA’s Graeme Davis said gusty north to north-westerly winds would increase the risk before a cool change came through in the afternoon.

He said there was plenty of grass ready to burn across Victoria.

“Certainly in the grasslands the fuel loads are very heavy, especially the grasslands around Melbourne and Geelong, the Gippsland and the northeast foothills and the goldfields, Ballarat area,” Mr Davis said.

“All the grasslands, are now fully cured and ready and able to burn.”

The Victorian Government has brought in a former US military Black Hawk helicopter from New South Wales to assist with any potential firefighting efforts.

Emergency Management Commissioner Craig Lapsley said the helicopter would be based in Ballarat in western Victoria.

“This’ll be the first opportunity that we’ll have not only to operate [it] in the fleet, but it’ll fight fires if they’re running,” he said.