The Met Office answers the question on everyone's lips: will it be a white Christmas?
Will it be a white Christmas?
For many of us, snow is synonymous with Christmas. Christmas cards, songs and movies all portray a 'white Christmas'.
However, for most parts of the United Kingdom, Christmas is right at the beginning of the period when it's likely to snow. Looking at climate history, wintry weather is more likely between January and March than December. Snow or sleet falls on average 5 days in December, compared to 7.6 days in January, 6.8 days in February and 6 days in March.
White Christmases were more frequent in the 18th and 19th centuries, even more so before the change of calendar in 1752 which effectively brought Christmas day back by 12 days. Climate change has also brought higher average temperatures over land and sea and this generally reduces the chances of a white Christmas. However, the natural variability of the weather will not stop cold, snowy winters happening in the future.
What is a white Christmas?
For many people, a white Christmas means a complete covering of snow falling between midnight and midday on 25 December.
However, the definition used most widely, notably by those placing and taking bets, is for a single snowflake (perhaps among a mixed shower of rain and snow) to be observed falling in the 24 hours of 25 December.
What is the likelihood of a white Christmas?
We cannot forecast the likelihood of snow on any given Christmas Day until 5 days before. In terms of the statistical likelihood of snow based on climatology, we know that a snowflake has fallen on Christmas day 38 times in the last 51 years, therefore we can probably expect more than half of all Christmases to be a 'white Christmas' in this sense.
Snow lying on the ground on Christmas Day - as we would expect from typical Christmas scene - is much rarer. There has only been a widespread covering of snow on the ground (where more than 40% of stations in the UK reported snow on the ground at 9am) 4 times in the last 51 years.
When did we last have a white Christmas?
Christmas 2010 was the last white Christmas. It was extremely unusual, as not only was there was snow on the ground at 83% of stations - the highest amount ever recorded - but snow or sleet also fell at 19% of stations.
We also had a white Christmas in 2009, 13% of stations recorded snow or sleet falling, and 57% reported snow on the ground.
Read more on metoffice.gov.uk