Even a little rain in areas most affected by recent downfalls could cause further flooding, the Met Office has warned.
There are 81 flood warnings and 155 flood alerts in place for the weekend and two severe warnings, meaning there is a potential risk to life.
Many areas have been left struggling to cope in recent weeks as England has been hit with 141% of its average February rainfall so far.
The damage wreaked by Storm Dennis last weekend and Storm Ciara the week before is projected to run into the billions to repair.
But the Met Office has warned there is more misery on the way, with weather warnings in place for North Wales, north-west England and North Yorkshire.
Luke Miall, a meteorologist at the Met Office, told the PA news agency: “Even small amounts of rain could lead to some further flooding just because the ground is so wet after the recent wet weather that we’ve been seeing.”
There are also warnings in place for strong winds in Scotland, Northern Ireland and the northern English counties, with gusts expected to reach 50mph to 60mph, perhaps even 75mph.
It will be unsettled throughout tomorrow morning, with a #wind warning in force for the north of England, Scotland and Northern Ireland. #Snow also likely on hills in the north pic.twitter.com/yzrlaQOfTb
— Met Office (@metoffice) February 21, 2020
A yellow warning is in force for snow and ice across much of Scotland above 200m on Saturday.
Mr Miall said the southern counties of England and Wales as well as the Midlands and East Anglia were looking a bit drier for Saturday, before the tables turn on Sunday.
“On Sunday we are going to see the wetter weather transfer further south – South Wales will probably see the brunt of the rainfall so we have got another weather warning in force for them.”
He said there would also be rain for south-west England and the southern English counties on Sunday.
Meanwhile, the deluge will let up a little further north.
“There will be some showers around for Scotland and perhaps Northern Ireland, but generally speaking northern areas will have lighter winds, a bit more in the way of sunshine and a little bit of a respite compared to what we are going to see on Saturday,” he said.
Large areas of South Wales and the Midlands continue to battle extensive flooding and massive clear-up operations have started where water levels have fallen.
Prince Charles visited flood-hit Pontypridd in South Wales on Friday which has been badly hit.
It is estimated that 1,100 properties – both residential and commercial – have been affected in the Rhondda Cynon Taf area.
Charles walked down Pontypridd’s high street, where many shops are closed due to flood damage.
He also went into The Prince’s cafe, which has been open since 1948, and saw how water had ruined the basement where bread is baked.
The prince met emergency workers and council staff at the Municipal Building, as well as residents and landlords affected.
Caroline Douglass, director of incident management at the Environment Agency (EA), said on Friday: “This will be the third weekend of exceptional river levels and stormy weather.
“With the effects of climate change, we need to prepare for more frequent periods of extreme weather like this.
“People need to be aware of their flood risk, sign up to flood warnings, make a flood plan and not to drive or walk through floodwater.”
The EA said that river levels have exceeded existing records with the Colne, Ribble, Calder, Aire, Trent, Severn, Wye, Lugg and Derwent among the many rivers where records have been broken.
But the agency said that, even with record river levels, the number of homes flooded has been fewer than in other major flood-events of the last 20 years.
Honister Pass in Cumbria, one of the wettest areas of the UK annually, recorded 185mm of rain in 36 hours on Thursday while 72mm was recorded in Shap, Cumbria.
Capel Curig in Snowdonia, north Wales, recorded 86mm of rain in 36 hours after setting Wednesday’s record for rain with 80mm in a single day.
A fundraiser launched by Good Omens actor Michael Sheen on Wednesday evening has made £41,338 for Welsh people affected by Storm Dennis.