Keeping warm has become more expensive as coal-fire power outages take a toll on Australia's energy market.
Prices rebounded significantly between April and June because of outages and colder-than-average weather, the Australian Energy Market Operator says.
Wholesale electricity prices, or those paid by retailers before they supply to customers, averaged $95 per megawatt hour.
This compared with $37 per megawatt hour in the first three months of 2021.
The price hikes were driven largely by coal-fired power station outages.
A turbine hall exploded at Queensland's Callide Power Station in May.
It tripped generators and transmission lines, leading to volatile prices in that state and NSW.
Meanwhile, flood damage at Victoria's Yallourn power station in June meant three units were taken offline for repairs.
Gas-powered generation provided backup for Callide and Yallourn, and prices went up for the east coast.
They averaged $8.20 a gigajoule for the April to June quarter, nearly double the price from the same period in 2020.
They also increased from an average of $6.03 a gigajoule between January and March this year.
Australia has the world's seventh-highest wholesale gas prices, according to the Institute for Energy Economics and Financial Analysis.
Colder-than-average weather across the eastern seaboard compounded price pressures, AEMO said.
National energy market demand for the second quarter rose by 250 megawatts compared to the same period in 2020.
This reversed a downward trend since 2018.
Perth had its coldest June in 31 years.
There was a 71 per cent rise in heating requirements compared to the second quarter of 2020.
