The Met Office has put out a statement that includes the following:
“This series of winter storms has been exceptional in its duration, and has led to the wettest December to January period in the UK since records began.
The severe weather in the UK coincided with exceptionally cold weather in Canada and the USA. These extreme weather events on both sides of the Atlantic were linked to a persistent pattern of perturbations to the jet stream, over the Pacific Ocean and North America.
The major changes in the Pacific jet stream were driven by a persistent pattern of enhanced rainfall over Indonesia and the tropical West Pacific associated with higher than normal ocean temperatures in that region. The North Atlantic jet stream has also been unusually strong; this can be linked to exceptional wind patterns in the stratosphere with a very intense polar vortex.
As yet, there is no definitive answer on the possible contribution of climate change to the recent storminess, rainfall amounts and the consequent flooding. This is in part due to the highly variable nature of UK weather and climate.
Nevertheless, recent studies have suggested an increase in the intensity of Atlantic storms that take a more southerly track, typical of this winter’s extreme weather. There is also an increasing body of evidence that shows that extreme daily rainfall rates are becoming more intense, and that the rate of increase is consistent with what is expected from the fundamental physics of a warming world.”
You can read more at the Met Office website: http://www.metoffice.gov.uk/research/news/2014/uk-storms-and-floods