Motorists have been urged to fill up ahead of the public holiday or risk paying more than $2 a litre at the pump.
Petrol prices are starting to rise across the country, with a peak price of $2.12 displayed at inner-city petrol stations in Sydney.
But the average price is sitting at $1.68 and motorists can still find fuel for as little as $1.54 a litre, amounting to a 58-cent difference between the cheapest and most expensive fuel.
Compare The Market energy expert Chris Ford said Sydney's upwards phase of its fuel cycle was just beginning and a new cycle could be imminent for Brisbane and Melbourne.
There's a 38-cent difference between the cheapest and most expensive fuel in Melbourne and an 18-cent difference across peak prices and low prices in Brisbane.
Mr Ford said servos commonly hiked prices ahead of public holidays.
"But after four weeks of prices falling, many retailers are choosing to delay increasing their prices," Mr Ford said.
For people travelling over the holiday period, he recommended filling up before heading home to avoid higher prices on their return.
He also said petrol stations in high-traffic areas, such as arterial roads, often charged more, and urged consumers to hunt around for cheaper offers.
NRMA spokesman Peter Khoury said oil prices were falling, allowing petrol prices to moderate from the $2-a-litre highs seen in mid-2022.
"Finding the cheapest fuel around and filling up now while prices have bottomed out could help a family driving a standard family sedan as much as $30 on a tank of fuel and among skyrocketing inflation that will go a long way to helping families," Mr Khoury said.
Average petrol prices vary markedly across the major cities, with motorists paying around $1.80 a litre in Hobart, $1.77 a litre in Canberra and 1.74 a litre in Adelaide.
Motorists in Brisbane, Darwin and Melbourne are also paying above $1.70 a litre, on average, while Perth drivers are looking at prices under $1.70 a litre.