Warm weather predicted for Christmas and snow in New Year

But once the festive season is over, Britain can expect to be covered in a thick blanket of snow.

Forecasters predict a wet Christmas followed by blasts of heavy snowfall in January and February as icy winds blow in from Russia and Scandinavia.

The cold snaps will follow what is expected to have been the hottest year ever in the UK since records began in 1659.

The scorching summer and warmer than average autumn means 2006 is on course to beat the previous hottest year - 1990, when the average was 51f (10.67c).

Monday was the warmest December night on record with a minimum temperature of 56f (13.6c) in the South East - three degrees above average.

Temperatures yesterday soared to 57f (14c) in parts of Eastern England, compared to average temperatures of around 47f (8c) at this time of year.

And it's not just Britain that is sizzling, as the planet as a whole is heading for its hottest ever decade due to global warming.

The unusually mild winter months will be interrupted by cold snaps, the Met Office said.

Heavy snowfall will be caused by the El Nino weather phenomenon, which happens once every few years off the west coast of South America.

The surface of the ocean becomes much warmer than usual for a few weeks due to an absence of the normal upwelling of cold, nutrient-rich water. This has a knock-on effect around the globe.

Met Office spokesman John Hammond said: 'In the past, El Nino conditions have often been accompanied by colder than normal winter spells, as there are more incursions of cold, dry air from Northern Europe and Russia.

'When this changes and moist, warmer air comes in from the Atlantic, you often get snow, so we could get more snow than usual this winter.'

He added: 'Winter temperatures are expected to be slightly warmer than average, but there will probably be a higher frequency of cold spells in February, which are more noticeable because of the mild winter.

'December will continue to be mild and fairly unsettled and above average rainfall is likely to continue through much of the month. Christmas is a bit early in the season to get the El Nino effects.

'For winter as a whole, our estimates slightly favour average or above average levels of rain.'

However, he warned that this winter's forecast could change, saying: 'The uncertainty surrounding the influence of El Nino remains key to the forecast and will continue to be monitored.'

The Met Office said it would be studying weather data in the next few weeks to establish whether this year's weather has propelled 2006 to be the warmest year on record after a scorching summer and record-breaking temperatures in July and September.

Mr Hammond continued: 'We will be looking more closely at the figures in the next week or so. It is certainly going to be one of the warmest years, but whether it will be the warmest on record remains to be seen.

'Globally, it also looks like it will also be one of the warmest ten years on record, but again, we don't know exactly where it will be in relation to other years.'