In parts of southern England, rainfall figures beat a record set in 1988
Early figures suggest parts of England have had their wettest January since records began more than 100 years ago.
The Met Office said much of southern England and parts of the Midlands had already seen twice the average rainfall for January by midnight on Tuesday - with three days left in the month.
And it is warning of more rain, as well as snow and high winds, for much of the UK in the coming days.
In Somerset, the military is preparing to help flooded areas.
Up to and including January 28, the South East and central southern England had 175.2mm (6.9in) of rainfall in January - beating the previous record of 158.2mm for the same parts of England set in 1988.
Across south-west England and south Wales, the 222.6 mm (8.8in) of rainfall up to midnight on Tuesday meant January 2014 was already the fifth-wettest on record.
On Wednesday, Environment Secretary Owen Paterson said military amphibious vehicles could be deployed to help flood victims in Somerset.
Military planners met council officials earlier, and discussions are believed to be continuing.
Mr Paterson will chair a meeting of Cobra, the government's emergency response committee, later.
Roads round villages such as Muchelney in the Somerset Levels have been cut for almost a month and about 11,500 hectares (28,420 acres) of the Levels are flooded by about 65 million cubic metres of water.
BBC Weather forecaster Emma Boorman said Thursday's weather would be "quieter" than recent days of heavy rain.
She said the South West would be "largely dry" with an "outside chance" of showers, while showers would be more likely in the Midlands, South East and east of England.
'No dry spell'
The Met Office has issued numerous yellow warnings - the lowest of its three alert levels - for the next few days.
A rain warning for south-east England expires at 12:00 GMT, but a new warning covering most of southern England, southern Wales and parts of Northern Ireland has been issued for the period from 08:00 on Friday until the early hours of Saturday morning.
Parts of central Scotland and northern England are being warned of snow on Friday.
The Met Office is also warning of high winds for many western parts of the UK on Saturday and Sunday.
BBC Weather presenter Nick Miller said the long-range forecast suggested there was "no prolonged dry spell in sight".
Parts of Somerset have been flooded throughout January
Fire crews and other rescue workers may now be assisted by military personnel in Somerset
The Environment Agency has numerous flood warnings and alerts in place, the majority in southern England.
Mild temperatures
For the UK as a whole, 164.6 mm (6.5in) of rain has fallen so far this month - 35% above the long-term average.
The figures will come as no surprise to those in the country who are continuing to suffer the aftermath of severe winter floods.
But the Met Office said it had seen a contrast from south to north across the UK, with northern Scotland having received 85% of its long-term average rainfall so far this month, compared with 200% over southern England.
Wet weather in winter usually means temperatures have been mild, and the UK mean temperature up to 28 January was 4.9C (41F) - 1.2C above average.
Met Office analysts said the whole of the UK was on target for a wetter than average winter.
The South East and central southern England are already seeing their sixth-wettest winter since record began in 1910 and the wettest since 1995 (369.7mm of rain). The wettest winter on record was 1915, with 437.1mm.
The main reason for the mild and wet weather so far was a predominance of west and south-west winds, bringing in mild air from the Atlantic, the Met Office said.
The BBC News Channel is providing live coverage from some of the worst-affected areas throughout the day.
