According to William Hill, this year sees the shortest odds ever offered this near to December 25th, with a surge of betting prompted by the early freeze.

It’s offering 5/6 on Aberdeen having a white Christmas, with Edinburgh, Glasgow and Newcastle at 11/10 and London and Liverpool priced at 6/4.

Paddy Power has London at 10/11, with most Irish locations at evens (and Lanzarote at 25/1 – good luck with that).

But all bookies agree that punters need to be sure they know what counts as a white Christmas before they decide to take the plunge and risk actual money.

William Hill spokesman Rupert Adams said: “The definition of a white Christmas is for one flake of snow to fall over the 24hr period of Christmas day, confirmed by the Met Office. So snow already on the ground does NOT count as a white Christmas for bookies.”

And Ladbrokes added: “The rules state that while a single flake is enough throughout the 24-hour period of Christmas Day, it must be snow – hail, ice pellets or soap powder will not count.”

Paddy Power operates to a slightly different set of criteria – being Irish, it doesn’t use the UK’s Met Office but instead relies on wunderground.com, the service that provides the six-day forecasts offered on this site (see below).

But it, too, insists that snow must actually come down on the day rather than lie on the ground from a previous fall, warning “1mm of snowfall must be recorded as falling between 00:00 and 23:59 on Dec 25th 2010”.

If you’re planning on having a flutter anyway, the Met Office produces a detailed and attractively-presented factsheet on the frequency of white Christmases in this country, which you can download as a PDF here.

It’s the second year that the insurer – previously known as Norwich Union – has sent out texts in the hope of reducing its customers’ exposure to costly disasters.

This year’s message says:

Please take care in the cold weather, if you have to drive, take a spade, food and a blanket. At home, leave the heating on to avoid burst pipes.

(You can find more of the items you should carry in your car on our winter driving page here.)

Aviva claims director Rob Townend pledged that the messages were only being sent to customers who had voluntarily supplied their mobile numbers and opted in to receiving texts from the company.

He said: “Obviously when we have such extreme weather conditions, as we have now, it makes sense to send advice to customers as quickly and simply as possible, so where we have mobile numbers for our customers – and they have said they are happy for us to contact them – we are sending little reminders to be extra careful in the cold snap.

“We hope it might prevent some of the soaking homes that we saw last winter as a result of water-damage caused by burst pipes and perhaps a short message about the driving conditions might make people think twice before they venture out in their cars.”

By coincidence, the name Aviva can mean ‘Spring’ in Hebrew (according to Wikipedia, anyway). Can’t come soon enough, we say.

Faced with a cold morning, a colder car and a tricky commute, many drivers like to check their vehicle will start in advance of needing it – and then leave the engine on to get a head-start in dealing with iced-up windows.

Quoted in today’s Independent, the AA’s Andrew Howard said: “The trouble is, there are idiots leaving their engines running to defrost the windows and warm up the car. They go back indoors to carry on getting ready while leaving the car running. The thieves know this and will walk around looking.”

But not only are thieves well aware of the opportunity this gives them, insurers are also unimpressed by this less-than-clever behaviour.

Also in The Independent, the RAC’s Vicki Burn adds: “If they turn their engines on and go indoors and the car is stolen, the insurer won’t pay out. It is not really a very clever thing to do.”