Festivalgoers at a music festival in Victoria’s Grampians have been advised to leave amid the extreme heat and fire danger, while Melbourne’s iconic Moomba Parade has been cancelled due to soaring temperatures.

Residents across four states have been experiencing stifling conditions, with high temperatures forecast over the long weekend in many parts of the country.

Moomba Parade organisers said the difficult decision was made “to ensure the health and safety” of performers, spectators, workers and volunteers. The wider festival will still go ahead, with some interruptions.

In an Instagram post, Pitch music and arts festival said the Country Fire Authority had advised the safest option for those already on site was to leave on Saturday morning due to the bushfire risk. The festival – which is due to run from 8 to 12 March – is at Moyston, where temperatures are forecast to reach 38C on Saturday and 39C on Sunday.

“If you are arriving on Saturday we recommend delaying your arrival until further notice,” the post read.

“The forecast tells us to expect hot weather each day of the festival. In addition, overnights will also be warm.”

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The CFA said its general advice for people in an area with an extreme fire danger rating, like the Pitch festival, is to leave early in the day as the safest option.

There are no extreme fire danger ratings forecast across the state on Sunday.

The festival had organised free shuttle buses running from Pitch to Ararat station on Saturday, for those wishing to leave. Organisers said they were working closely with authorities and that there were no active fires in the region.

In a statement, Pitch festival organisers said programming would commence at 6pm on Saturday and will continue as scheduled for the remainder of the event. Organisers said they are working “through the specifics” in relation to refunds, and ticket holders would “receive an update as more information becomes available”.

Prior to the program resuming at 6pm, the festival will offer “light entertainment under the shade”, including yoga, to ensure patrons “are not remaining in their campsites in the heat of the day”.

Pitch’s Instagram post has more than 800 comments, with some questioning why the festival had not been cancelled.

One person at the festival commented that they had to pay for wifi at a food stall to access the information.

“All of the sets at the stages stopped without warning and I had to walk around and ask people if they knew what was going on,” they wrote.

Another said their group had left the festival on Saturday morning and were feeling “incredibly frustrated” about missing the performances, but also about the money they had spent.

Artist Bailey Ibbs confirmed on social media he would not be playing his set on Saturday night as planned.

“Due to advice from the CFA, I’m incredibly upset and gutted but that’s life,” he wrote on Instagram.

In a post to Facebook, the local Moyston CFA brigade said it is meeting daily with event organisers.

“We continue to work with [and] wish the festival all the best for a safe [and] successful event,” it wrote.

The Golden Plains festival, which is taking place just under two hours away from Pitch, says it is going ahead. Gates opened at 8am on Saturday.

Victoria, South Australia, Tasmania and New South Wales were set to experience stifling conditions from Saturday through to Monday.

A total fire ban was in place across five districts in Victoria on Saturday. The ban applies to the Wimmera, west and south Gippsland, central, north central and southwest regions.

Across the state, 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 south-west 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.

Dangerous fire conditions are forecast to ease across Victoria from Sunday.

Meanwhile, the mercury is set to reach the low 40Cs in South Australia as severe heatwave conditions extend farther 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.

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, 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.

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

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