Firstly a major winter storm on the 5th and 6th brought strong winds to Scotland with a storm-surge along the east coast of England. This was followed by a succession of deep Atlantic low pressure systems bringing heavy rain and very strong winds with frequent gusts of 60-70mph on 18/19th and 23/24th December.
December was in fact the windiest December in records from 1969 and one of the windiest calendar months since January 1993. It was also the wettest December in a series from 1910 in Scotland.
So why has it been so stormy? The jet stream (a narrow band of fast-moving winds high up in the atmosphere) has been particularly strong and when this happens storms can cluster together over a period of time.
Is it getting more stormier in Great Britain? There is no evidence to suggest the UK is increasing in storminess. The Atlantic Ocean is in a natural warm phase at the moment and during these times, gales and flooding episodes are more frequent for the UK. It is natural for our weather to be highly variable and the winds in the upper atmosphere direct where the depressions and high pressure areas move. It is more likely to be luck or bad luck on where the jet stream sits in relation to the UK. The weather around the world is interconnected and it's possible that the recent extreme cold spell over the USA strengthened the part of the jet stream over the UK.
The map above from the Met Office shows the rainfall anomaly in December as a percentage of average against the 1981-2010 climatology.