Residents in four states are experiencing stifling conditions, with soaring temperatures over a long weekend in many parts of the country.

South Australia, Victoria, NSW and Tasmania are set to experience stifling conditions from Saturday to Monday.

The mercury is set to reach the low 40Cs in South Australia as severe heatwave conditions extend further west of the Eyre Peninsula over the long weekend.

The Bureau of Meteorology warned of a prolonged run of heat from Ceduna to Port Lincoln, Adelaide, the Barossa Valley, Narracoorte and Mount Gambier.

The state government activated a code red response late on Friday, with additional services available to people sleeping rough.

Adelaide is in the midst of its busy festival period and many have triggered heat plans, including the Fringe Festival, the South Australian athletics championship and the Adelaide Cup horse race.

Harness and greyhound races have been rescheduled in many instances.

Victoria’s Labor Day long weekend started with a total fire ban in five districts on Saturday before dangerous fire conditions are forecast to ease from Sunday.

The ban applies to the Wimmera, west and south Gippsland, central, north central and southwest regions.

A severe heatwave is sweeping the state’s south, with the bureau warning it’s likely to be felt across a large area, including Melbourne, Ballarat, Horsham, Warnambool and Bairnsdale.

Melbourne is tipped to reach a top of 39C on Saturday, while conditions are set to hit 41C at Warrnambool, Torquay and Avalon.

The state’s central district is slated to reach 41C and 40C is forecast for popular holiday towns along the Murray River.

The southwest is expected to record its sixth-highest maximum temperatures on record in some areas.

“We have only seen three consecutive days of above 38C in Melbourne three times during March in the past 100 years,” Bureau of Meteorology senior meteorologist Lincoln Trainor said.

Overnight minimum temperatures were also expected to break records, with a minimum of 25.6C forecast for Melbourne Olympic Park its highest in 11 years of operation.

Extreme and severe heatwave conditions have also hit Tasmania, with warnings or much of the state’s north and northeast.

Areas affected include Burnie, Devonport, Launceston, Richmond, Swansea and Whitemark.

Hobart is expected to reach at least 35C on Saturday, and may break its minimum March temperature record of 21.1C on Sunday, Mr Trainor said.

There will be relief for King Island on Sunday but that’s not expected to flow through to the rest of the state until Tuesday.

“The heat will begin to break for Victoria and Tasmania during Tuesday when winds turn southerly and the lingering trough over the southwest of Victoria moves east into the Tasman Sea,” Mr Trainor said.

“Temperatures will still remain quite hot in northern districts of Victoria until Wednesday and Thursday, when temperatures slowly drop back to the March average.”

Southern NSW is also experiencing a severe heatwave with temperatures set to reach the high 30Cs in several areas including the Riverina, Lower Western, Upper Western and South West Slopes.

Conditions are expected to ease from the middle of next week.

This post was originally published on Michael West.