Petrol prices are set to soar as Aussies get prepared for the long weekend.

Peter Khoury from the NRMA in Sydney told Today that most capital cities will see prices above 140 cents a litre, and branded the hike "appalling".

"It's particularly appalling," Mr Khoury said, adding "I would be social distancing myself from all companies from the next week or so at least.

"The price cycles in Australia are now defying gravity. They are going up three times faster than they fall.

"It's absurd in the middle of a pandemic to be doing this when we know so many families are struggling. I'm lost for words, to be honest."

Sydney is tipped to hit 145 cents a litre, while both Brisbane and Melbourne will see prices of 150 cents a litre.

Perth will hit 137.5 cents a litre and Adelaide is a bit lower hitting 139.2 a litre.

Canberra and Hobart will hit 125.0 cents a litre and Darwin will have the nation's lowest prices at 119.2 cents a litre.

Mr Khoury urged shoppers to use fuel comparison apps to get the most bang for their buck.

"We're getting ripped off," he said.

"In every one of those cities, there are a whole bunch of servos that are still sitting between $1 and $1.10 some $1.15, go and find them. Fill up there.

"Drive past the $1.50 servos, don't give them your business, go to the cheaper servos... as long as we put our money into those servos we will keep having some degree of competition."