The Met Office has warned that Britain faces a higher risk of a colder and less-windy winter, fuelling fresh fears of energy shortages.
Its three-month outlook has highlighted the odds for a harder time ahead that would ratchet up the pressure on Britain's energy supplies.
There is said to be a 25% chance of the winter being colder than normal, which would create more demand for heating.
In addition, there is a 25% probability of a less-windy period - which could mean less electricity generated by wind turbines.
David Cox, an independent energy analyst, has warned that energy supplies would remain "tight" this winter, regardless of the weather.
"If we have a mild winter, we might scrape through by the skin of our teeth if we have no other technical problems. But if we have a cold winter, I think it's likely that we will see blackouts," he told the Telegraph.
Bidding war
Mr Cox also warned that a cold snap risked sucking the UK into a bidding war with other rich nations for liquified natural gas.
Gas prices have fallen sharply in recent months after a warmer-than-normal autumn and a successful drive to fill storage across Europe.
Meanwhile, National Grid stressed today that blackouts in Britain would be a last resort this winter if energy supplies run low.
Its boss, John Pettigrew, said its "base case" assumption was the UK would have enough supplies to meet heating and lighting demand this winter.
However, he added that short rolling power cuts were a possibility.
"There could be energy shortfalls in the UK and we will manage that very carefully," Mr Pettigrew said. "This isn't a time for people to panic."
Ready for the winter
"Most importantly what we're doing is making sure that the infrastructure that we have and the networks are robust and ready for the winter, and I've got thousands of engineers making sure that the network is ready for whatever weather we see over the winter."
Mr Pettigrew told the BBC the company was working on a number of scenarios to protect the country against any energy supply shortfall.
The first option would be to increase supply by restarting mothballed coal-fired power stations. The next step would be to pay households and businesses to reduce consumption during peak times, with short rolling regional outages a last resort.
The International Energy Agency warned last month that Europe must slash its gas consumption to prevent the risk of power rationing and widespread blackouts this winter.
It said that the Continent and the UK needed to voluntarily reduce gas demand by 13% in order to remain "safe and secure" if there was no Russian gas.