This year is set to become the wettest on record in the UK, forecasters said, as flood-battered areas were warned they face renewed danger from storms bringing a wet and windy end to 2012.
London's flood defence system was activated on Thursday for the first time since 2010 as Britain's wet weather threatens to bring flooding to the capital.
The Environment Agency raised the Thames Barrier as Britain faces more potential torrential rainstorms as an Atlantic storm heads for the country.
That alone could bring up to 2in of rain and 80mph winds in some areas this weekend as bands of persistent rain move into and across England and Scotland, according to MeteoGroup.
Provisional figures show that just 1.8in of rain is needed from December 27 to 31 for 2012 to be the wettest year on record for the UK overall, with a new record already set for England with 43.1in (1,095.8mm) falling between January 1 and Boxing Day, the Met Office said.
The UK as a whole has had 50.8in of rain from January 1 to December 26, with the wettest year on record for the UK currently 2000, when 52.6in fell.
The figures came as people living in parts of Britain already hit by floods were told to expect more misery as another barrage of heavy rain comes in from the west.
The Environment Agency said that the west of the UK should prepare to take the brunt of the wet weather, with many areas still saturated with water from before Christmas, when floods forced many to flee their homes.
"The weather is set to remain unsettled into the weekend. With the ground still very wet, and river levels running high, any rain is likely to increase the risk of flooding," an EA spokeswoman said.
"There is also an ongoing risk of flooding from groundwater, particularly in Dorset, and some larger rivers like the Thames and Severn are still rising as they slowly respond to the recent downpours.
"As a result, we may see further flooding of low-lying land, such as flood plains and low-lying roads as the peak in river levels moves downstream."
The Met Office said new regional rainfall records have been set in several areas of England, including northern England, east and north east England, the Midlands, and East Anglia.
The recent heavy rain, coupled with late-running engineering work and other problems, meant a miserable return to work for rail travellers after the festive break.
First Great Western said the main line in the South West, which has been closed since before Christmas because of flooding between Exeter St Davids and Tiverton, is expected to reopen on Saturday.
The Environment Agency currently has 84 flood warnings and 191 flood alerts in place across the country, with the Midlands and the South East worst affected.
The British Geological Survey has an amber landslide warning in place for the South West, urging walkers to take care along coastal routes.
Stormy weather has already been blamed for fires at a school and hotel within a few miles of each other in Dorset this morning.
Lightning is believe to have started blazes at Lytchett Minster School and the derelict Cliff House Hotel in the Boscombe area of Bournemouth.
In a third incident, 20 sheep died in a barn fire at Stalbridge, near Shaftesbury, with lightning during storms in the county overnight again suspected as the trigger for the blaze.
Although sunshine will break through at the weekend, intermittent persistent bands of rain and stormy showers will plague Britain until the New Year.
Gareth Harvey, forecaster at MeteoGroup, said the weather would present a "messy picture" into next week but that there were signs it could settle after that.
"There will be more rain and strong winds over the next two to three days," he said.
Friday night and the early hours of Saturday morning are set to see the worst of the stormy weather, with winds hitting 80mph in areas including north east Scotland and the Western Isles.
A band of rain will also move south and east from Scotland overnight to cover the south east quarter of England on Saturday, before dying out in the afternoon.
The winds will drop on Saturday - but remain quite strong - with more showers, some of them heavy, coming in from the west.
There will be some bright patches, Harvey said, but almost anywhere could see a shower.
More showers will come into western Britain and Northern Ireland on Sunday.