Mist and lingering fog is threatening to mar revellers' enjoyment of tomorrow night's New Year's Eve fireworks displays, forecasters said.
After weeks of snow and ice, the bitterly cold weather has given way to a welcome rise in temperatures across the UK.
But despite the big thaw, increasingly warmer air has reacted with the cold ground, throwing a haze of fog and mist across much of the country this week.
Weather experts predict this murky blanket shows no sign of easing, meaning hundreds of traditional New Year's Eve firework celebrations will be cast against a dull, rather than crisp winter sky.
Met Office forecaster Mark Seltzer said: "It will be mostly cloudy across the UK tomorrow with mist and fog patches and the odd bit of drizzle.
"The general outlook is quite murky and fog combined with the low-lying cloud is going to prove problematic for fireworks displays."
Aisling Creevey, of MeteoGroup, the Press Association's weather division, added: "I don't think it will be as spectacular as it would be on a clear night.
"Visibility is not looking great.
"People will still be able to see the fireworks but perhaps not as spectacularly."
Weather experts predicted that the mist, fog and cloud will disperse most rapidly in Scotland as winds get stronger.
They predicted that it would stay dry in most places in the UK tomorrow with temperatures remaining reasonable for the time of year.
In London evening temperatures are expected to reach 6C, while in Edinburgh, New Year revellers are expected to face lows of between 1 and 2C.
The foggy conditions have promoted a number of warnings from authorities over the past week.
The RAC have advised motorists to take extra care driving through pea-soupers.
Its spokesman said: "Motorists should drive appropriately and leave plenty of distance between the vehicle in front."
Coastguards also warned sailors to check their vessel and weather forecasts before setting out to sea.
Bernie Kemble, Swansea coastguard watch manager said: "The break between Christmas and New Year might seem like an ideal time to take out a boat, but low visibility makes it extremely challenging to navigate a vessel safely or to give an accurate location if you get into difficulty."
A spokeswoman for airline Flybe said 64 of its inbound and outbound flights from Southampton were affected by fog yesterday, with planes being cancelled and diverted to Birmingham, Exeter and Bournemouth.