Britain's biggest energy supplier British Gas will increase prices by an average 9.2 per cent from 23 November.
With rival SSE set to hike prices for its customers the week before by 8.2 per cent – and the other "big six" firms set to announce similar rises – experts are urging households to fix rates now, not just switch, as suggested by David Cameron.
The Prime Minister sparked a row on Thursday after he told struggling consumers that they should switch energy suppliers.
Clare Welton of Fuel Poverty Action said: "Switching from one expensive, profiteering company to another does not provide us with a solution." But his words apparently struck a chord with energy users who swarmed to comparison sites to switch.
James Padmore, of comparethemarket, said: "We've seen a huge surge in energy switching since the first price increases were announced – traffic to the energy-comparison section of our site increased by 300 per cent in the last week. On Thursday alone, as a result of the British Gas announcement, we saw a 212 per cent uplift in people switching their energy supplier."
But Martin Lewis, of Money Saving Expert, said: "The most important thing people need to know is – don't just do a comparison to ditch and switch. You'll simply end up going to the cheapest now, which will inevitably put prices up later. Instead, the smart move is to lock into a cheap, fixed-rate deal that guarantees no price hikes.
"Many people can cut their costs now and get this guarantee. But the window of opportunity is closing rapidly as, with the upward movement in prices, it's likely the current cheap fixes will be pulled and replaced by more-expensive versions."
Mr Padmore agreed. "Our advice is to switch and fix before all of the best fixed rates go and the rest of the price rises are announced," he said. "Some great tariffs include EDF Blue+ Price Freeeeze March 2017, the longest fixed tariff, and the Scottish Power Online Fixed Price Energy March 2015."
With prices soaring and the cold weather upon us, it seems the best way to ensure savings ahead is to pick a firm or tariff which has promised to freeze prices. Independent supplier First Utility, for instance, has promised to hold prices until after the winter while green supplier Ecotricity has promised no rise until January.
"If you want to protect yourself then the time for action is now," said Tom Lyon of uSwitch. "There are some great fixed-price deals on the market which can protect you from price hikes for anything up to four winters. This protection could be extremely valuable for those on a tight budget and could make all the difference in being able to afford to keep warm."
With Energy Saving Week coming up, he also pointed out that people can do more than reduce the cost of the energy they use. "Now is also the time to reduce the amount you use – not by going cold, but by making your home as energy efficient as possible."