Last December UK's coldest for 100 years

By Richard Black
Environment correspondent, BBC News

Image caption,
Crisp, wintry weather turned usually fluid attractions into static features

Last month was the coldest December documented for the UK since nationwide records began 100 years ago, the Met Office has confirmed.

For central England, it was the second coldest December since 1659.

However, the first analysis released of global temperatures shows 2010 was one of the warmest years on record.

The UK's harsh weather was caused by anomalously high air pressure that blocked mild westerly winds and brought cold air south from the Arctic.

The provisional monthly Met Office figures show the UK temperature averaged -1C - a long way below the previous coldest December, in 1981, which registered -0.1C.

The December average for the century-long series is 4.2C.

It was also the coldest calendar month since February 1986, the Met Office reports.

"It's been an exceptional month, there's no question about that - it will go down in history as one to remember," said chief meteorologist Ewen McCallum.

"Our records go back to 1910 and it's certainly the coldest since then, so it's the coldest December in 100 years," he told BBC News.

However, the month also turned out unusually sunny and dry.

Less than half the expected amount of precipitation (snow and rain) fell, making it the third driest December in the national data series.

And the country bathed in sunny conditions for nearly 40% longer than average.

As a whole, 2010 was colder in the UK than in recent years - the 12th coldest year in the series, but also among the 10 driest and sunniest.

Image caption,
December 2010 in graphics: "One to remember"

The Met Office has yet to release its global analysis.

But earlier this week the University of Alabama at Huntsville in the US, which collates temperature data gathered by satellites, declared it to be the second warmest year since the satellite record began in 1979.

"As far as the race for warmest year goes, 1998 (0.424C) barely edged out 2010 (0.411C), but the difference (0.01C) is nowhere near statistically significant," wrote Dr Roy Spencer on the project's website.

"So feel free to use or misuse those statistics to your heart's content."

The Met Office analysis, plus those from two other US centres, are anticipated later this month.

The sequence of unusually cold UK winter weather has raised the question of whether this is now the norm; but Mr McCallum urged caution in deducing patterns from what could just be natural variability.

"Variability is like a fruit machine: you can have a warm winter, a mild winter, three mild winters, you can have four cold winters," he said.

"Obviously there's something going on given we've now had three in a row - but we've had three wet summers in a row as well, and it's impossible to nail this and say 'that's because of this' - it's all part of variability."

It was not yet clear, he said, whether the 2010/11 winter would turn out to be unusually cold overall, given that we are little more than one-third of the way through the season.

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