A landslide warning has been issued by the Met Office, as continued heavy downpours sparked fears of unstable cliff faces.
Boxing Day walkers were urged to take extra care in "dangerous conditions" with flooding set to worsen across parts of England and Wales.
The Met Office, which issued the warning following advice from the British Geological Survey, said coastal areas in the south-west of England are in particular danger of collapsing cliff edges and rockfall, but stressed that all areas enduring heavy rain are at risk.
A spokesman for the Met Office said: "We have had such heavy and persistent rain fall over the last few days and weeks and that there is a danger of landslides and rockfall along the coast, even on coastal paths.
"We are advising Boxing Day walkers in the south-west of England to take particular care in these dangerous conditions, especially those not familiar with the area. Do not get too close to the cliff edge or walk under the cliff face along the beach and remember that coastal paths could be impacted too."
Many coastal paths have been closed over the last few weeks along the south-west and train services have been disrupted by small coastal landslides.
Weather experts said up to 15mm of rain fell across the south-west of England and south Wales, with up to 20mm expected again on Wednesday. Matt Dobson, a meteorologist for MeteoGroup, the weather division of the Press Association, said: "A band of rain will move eastwards across Wales and south-west England, with heavy rain falling mainly on areas that have already seen a lot, increasing the risk of flooding and causing river levels to remain high."
The EA has 151 flood warnings in place, which urge residents to take immediate action against expected flooding, while 252 less severe flood alerts have been issued across most of England and Wales. The Scottish Environment Protection Agency has removed all its warnings, with lighter showers expected only through the south-west of the country.
Around 470 properties have flooded since Wednesday, while Floodline revealed it has received 18,000 calls during the recent wet weather. The worst affected areas have been south-west England and stretches along the south coast from Cornwall to Kent, along with Wales and northern Scotland.
The soggy Christmas comes towards the end of what is expected to be one of the wettest years in Britain since records began. The UK's average rainfall in 2012, excluding December, is 1,202mm - placing it 13th in the list of wettest years since records began in 1910. The year 2000 remains the UK's wettest year, with an average rainfall of 1,337.3mm.