The number of severe flood warnings in place was increased to nine tonight as communities across Britain braced themselves for yet more rain misery.
A combination of rain, high tides and strong winds means there is a "strong risk" of flooding in coastal areas across England and Wales.
The Environment Agency has flood warnings in place throughout the country, while the Met Office has issued its own warnings of heavy rain and high winds of up to 60mph for many southern and western areas until tomorrow.
The nine severe flood warnings - meaning a danger to life - cover the coastlines of Cornwall, North Devon and the River Severn, the EA said.
It also warned of risks over the weekend to coasts and tidal areas of Dorset, Somerset, Bristol and Gloucestershire, saying that gales and big waves would combine to cause possible overtopping of flood defences and sea walls, property flooding and travel disruption.
There are nearly 150 flood warnings and more than 250 flood alerts in place across England and Wales.
Kate Marks, the Environment Agency's flood risk manager, said: "A low pressure system combining with high tides brings a risk of coastal flooding to many parts of England over the weekend.
"The risk is highest for south west England, although many coastal areas will be affected and the public should stay away from coastlines and tidal areas and not drive through flood water.
"At the same time the risk of river flooding continues for the southern counties as with the ground already saturated, rivers are very responsive to rainfall. Groundwater levels also remain high in southern counties."
A band of heavy rain sweeping swept across the South West, West Wales and southern England today, with 0.8in (20mm) to 1.2in (30mm) set to fall across many parts and as much as 1.6in (40mm) on high ground.
High tides will leave coastal areas in the South West at risk of flooding and parts of south-east England, the North West and Yorkshire and Hull coast will also be affected by the wind, rain and high tides in the next few days.
The forecasts will be met with trepidation by residents on the Somerset Levels, which has seen 25 square miles (65 sq km) swamped by the worst flooding in the area for 20 years.
Avon and Somerset Police said the EA's pumping operation on the Levels was the biggest the country has ever seen.
There are 62 pumps operating 24-hours a day, draining an estimated 1.5 million tonnes of water - the equivalent of 600 Olympic-sized swimming pools - from the Levels.
Personnel from all three branches of the Armed Forces are currently on stand-by to help villages cut off by the floods, and military planners met council officials and emergency services to discuss how to bring relief to communities, many of whom have been stranded since Christmas.
The Government and the EA have come under fire from MPs and local councils in Somerset, with accusations of under-investment in flood defence work.
There have been widespread calls for urgent dredging of rivers, but the EA insisted that would not have prevented the recent flooding.
On Wednesday, Environment Secretary Owen Paterson said dredging would be carried out on the Levels as soon as it is safe to do so.
But a senior Labour MP described the Government's decision to call in the military as "spin".
Emily Thornberry said the Coalition was making "policy by photo-opportunity" and added: "The spin we had was that the Prime Minister had called in the Army and then we see it's two majors who have gone home."
The Prince of Wales is expected to visit flood-affected parts of the Somerset Levels next Tuesday.
Meanwhile, flood barriers have been put up at Frankwell in Shrewsbury to protect against a rise in river levels on the Severn after heavy rain in Shropshire on Tuesday, and temporary defences are also set to be erected at Bewdley on the Severn.
In Wales, students in seafront halls of residence at Aberystwyth University are being evacuated today until 4pm on Monday as a precaution.
The latest poor weather conditions come at the end of a month which has already become the wettest January on record for parts of southern England.
Meanwhile, in Gloucestershire the authorities are preparing for this weekend's Severn bores and tidal surges.
A 4* bore is expected tomorrow morning and a 5* bore is likely to happen the following day.
It is one of Britain's few truly spectacular natural phenomena and sees a large wave surge up the Severn estuary.
Environment Secretary Owen Paterson said: "With more heavy rain and high tides expected to cause further flooding over the weekend I have chaired another COBR meeting to ensure everything that can be done to prepare, is being done.
"A number of severe warnings have now been issued and so I urge everyone to listen to all the advice being issued by the Environment Agency and emergency services.
"Environment Agency staff are working day and night, alongside the emergency services and other local specialist agencies, to get communities ready for the bad weather. Government continues to do everything it can to assist those affected in the Somerset levels."