The first snow has fallen and bookmakers have shortened their odds for a white Christmas. So far, so seasonal - but distinctly unusual weather conditions earlier in the year have raised the price of a traditional Christmas dinner.

It has been a Goldilocks year for British farmers, with the weather so wet at home that vegetable yields have been crippled, yet so dry in other parts of the world that imported animal feeds have jumped in price.

Now the effect is starting to be seen on British supermarket shelves. Many of the Christmas staples have shot up in price, and some may look different - for example, supermarkets are selling smaller sprouts.

The latest official inflation figures reveal food prices are rising at 3.9%, faster than overall goods and services.

So will this year's Christmas meal gobble up your seasonal budget?

TURKEY

For many, this is the highlight of the Christmas table and it is also the single most expensive item.

In the run up to Christmas 2011, Britain spent £113.5m on eight million birds, according to retail analysts Kantar Worldpanel.

British turkeys are fed on wheat and soya, both of which jumped in price in the middle of 2012, due to the worst droughts for decades in the USA, South America, Russia and Black Sea states.

Meanwhile, UK-grown wheat has suffered badly in the wettest summer for 100 years.

"It's tough this year for farmers," observes the National Farmers Union's Chris Dickinson, who says feed accounts for 60% of the cost of producing a bird.

"They can't cut back on feed because you don't want to compromise quality or bird welfare."

With Christmas such an important time for food farmers and retailers, it seems increased production costs are not being fully passed on to the consumer, at least where turkey is concerned.

Average price figures gathered by the Office for National Statistics (ONS) show turkey steaks have risen 11% in a year, and research carried out for the BBC by price monitors Mintec found the wholesale price of turkey had gone up by 4%.

But the supermarket price of whole birds appears to be largely static across the major retailers, with Tesco saying it had set its prices earlier in the year.

"The fierce competition to secure Christmas spending should shield customers from the full impact of rising costs," says Stephen Robertson, director general of the British Retail Consortium.

SPROUTS

Sprouts have been growing with the handbrake on Matthew Rawson, Brassica Growers Association

So much for the turkey, what about the trimmings?

The nation's children may cheer to find their parents scrimping on Brussels sprouts this year.

Although the Office for National Statistics does not track the diminutive brassica's price throughout the year, research carried out for trade magazine The Grocer found that the price for loose sprouts had jumped from £1.69 per kg last year to £2.10 this year - an increase of 24%.

The wet weather has led to falling yields, according to Matthew Rawson of the Brassica Growers Association, himself a sprout producer.

"Getting these little green gems of joy onto your plate is going to be a lot harder this year," Mr Rawson says.

Media playback is unsupported on your device Media caption Sprout farmer Martin Tate on the pressure of the Christmas rush

"We've had horrible weather to contend with, sprouts were not planted into ideal conditions, and then with waterlogged soil in July and August they didn't get the root development.

"This meant smaller leaves and we had less photosynthesis - they have been growing with the handbrake on."

Nevertheless, Mr Rawson insists that despite the low yield, growers will be working around the clock to satisfy the Christmas demand, which makes up a third of annual sprout sales.

Supermarkets, meanwhile, have widened the acceptable size range of the vegetable in order to "maximize every sprout".

POTATOES

The price of old potatoes, essential for those fluffy roasties, has shot up by 43% in the last year to 86p per kg, according to ONS November figures.

Farmers of the humble spud have had a difficult year. An early drought followed by the wettest summer since 1912 have led to poor growing conditions and a tricky harvest.

The Potato Council says it is the worst harvest since 1976 with yield down 15%, but rising costs as waterlogged ground has made for slow picking.

The small harvest has raised the trade price on the open market by 176% when compared with last year, a spokeswoman says, adding that consumers will find smaller potatoes than usual.

Lovers of other root vegetables will also have to dig deeper into their pockets this year, with the price of carrots up by 44% since last November.

SAUSAGES & BACON

"Pigs in blankets", sausage-meat stuffing, and maybe a gammon joint on Christmas Eve - pork products have high billing on the Yuletide menu.

As with turkeys, the price of pig feed has risen as a result of drought abroad and high rainfall at home.

These and other factors have led the National Pig Association to warn of a "worldwide bacon shortage" in 2013.

The UK imports 29,000 tonnes of pork a month and the European Union price has been pushed up to a three-year high as farmers cut their herds ahead of new welfare regulations in January.

But so far this year, sausage prices have only risen 2% while back bacon prices have stayed level according to ONS figures.

Richard Longthorp, chairman of the National Pig Association, says rising costs would force some producers out of business, but the knock-on effect would take 10 months to emerge.

"I wish it wasn't the case for the consumer's sake, but I think there will be a greater increase in pork price in Christmas 2013 as the shortages feed through," he says.

BREAD SAUCE

It is one of the little extras that makes Christmas dinner special, but the price of a key ingredient of bread sauce - a white sliced loaf - has already jumped 12% this year and is likely to keep on rising.

This year's British wheat crop was the poorest since 1977 and the UK is forecast to become a net importer of the grain in 2012-13, the Home-Grown Cereals Authority says.

Bakers are already warning that they are facing a 13% increase in the price of flour, some of which will be passed on to the consumer.

"We have taken a flour increase of £50 a tonne. At the end of the day, the manufacturer can't sustain that kind of increase," says the National Association of Master Bakers' chairman, Mike Holling.

"What we are seeing at the moment, even in the supermarkets, is a 400g loaf having to go up by 5p and an 800g can go up by 10p."

THE REST

If all this makes you reach for the booze (up 1.4%) then take some cheer: the dried fruit in your Christmas pudding is almost exactly the same price as it was a year ago, tangerine prices are steady and butter has softened in price.

Sadly, the price of chocolate coins is not tracked.