Christmas is just around the corner and it can be a busy time for a weatherman.
I do get asked to switch on Christmas lights, sometimes by friends in their own homes and at bigger venues too.
This year I've had the great honour of switching on the lights outside a doctors surgery in Pentyrch and at a garden centre in Pyle near Bridgend.
It gives me an opportunity to talk about the weather and tell a few Christmas jokes as well which either raise a few smiles or groans!
Here is one of my current favourites: 'What did Mrs Christmas say to her husband on Christmas morning when she looked outside? It looks like rain dear!'
At this time of year, (without fail) people ask me if we're going to have a white Christmas.
It can be a difficult question to answer, even a few days before the big day itself, especially if the computer models we use keep chopping and changing, increasing uncertainty in the forecast.
Many of us long for the scenes depicted on traditional Christmas cards and the annual interest in snowy Christmases goes back a long way.
It has its origins in the colder climate of 1550 to 1850, when Britain was in the grip of a 'Little Ice Age' and winters were much harder than they are now.
In Wales, snow is more likely in January and February; while this may come as a surprise but snow is more common at Easter than at Christmas when sea temperatures are lower.
For many, a white Christmas means a complete covering of snow on the ground, cars and roof tops.
However, the definition used most widely, especially by those placing and taking bets, is for a single snow flake (perhaps amongst a shower of rain and snow mixed) to be observed falling in the 24 hours of 25 December.
Snow already lying on the ground does not count as a White Christmas according to the bookies.
Snow on Christmas Day is quite rare. Since 1960, a white Christmas in Cardiff has occurred only 4 times, in 1990, 1993, 2001 and 2004.
December 2010 was the coldest for 100 years in the UK. On Christmas Day, snow fell at 19% of weather stations; while 83% of weather stations had snow lying on the ground - the highest ever recorded.
In complete contrast, Christmas Day in 2011 was very mild with a high of 13 Celsius recorded at Hawarden in Flintshire.
Snow at Christmas is a double edged sword; it is pretty to look at but it can be a real nuisance; making travelling difficult, especially for those undertaking long journeys and visiting relatives around the country.
As a boy I used to love snow but as a forecaster I am not so keen on it these days.
It is the hardest thing to predict and get right although it can snow as much as it wants when I am in the Alps skiing - I don't mind it so much then!
So what about this Christmas? The latest odds for a white Christmas in Cardiff are currently 6 to 1.
Looking at the latest charts I would say rain is more likely. The greatest risk of snow will be on the hills and mountains in the north of Britain, especially in Scotland which is to be expected.
Of course, there is still time for things to change with Christmas still just over a week away. So watch this space!
Personally, it would be nice to pull back the curtains on Christmas morning and see a covering of snow on the ground and roof tops but hopefully not enough to stop me from driving to my sister's in Barry for my Christmas lunch and going for a walk afterwards!
Happy Christmas/ Nadolig Llawen
Derek
