Flash floods hit large swathes of eastern England last night, causing power cuts and homes to be evacuated.
Meanwhile the British Red Cross today said they are "on standby" and have enlisted hundreds of volunteers to help anyone affected by the deluge.
More than a month's rain fell overnight in some parts of Britain, and more bad weather is expected tomorrow as the aftermath of Hurricane Bertha continues to wreak damage.
Fire crews in Norfolk, Cambridgeshire and Lincolnshire were inundated with emergency calls and battled through the night to pump water out of swamped homes.
Power cuts hit some 1,400 homes, but engineers restored electricity to everyone by 2am, while some drivers were forced to abandon their cars as they became marooned in flooded streets.
A Norfolk County Council spokeswoman said their fire department had received more than 100 incident calls from 6pm last night until this morning.
She said: "To have so many incidents is not common. We were receiving calls from residents who had been asleep and woken up to find that their homes were flooded or part of their property was flooded and were asking for our help or advice."
She said Norfolk fire services were taking part in a planned strike today, but said contingency plans are in place to ensure that all emergencies are dealt with.
Residents in East Walton in Norfolk posted photographs on Twitter showing entire streets left under water.
With further bad weather predicted, even emergency relief agencies are mobilising to offer help.
Head of UK emergency planning and response for the Red Cross, Simon Lewis, said: "We have hundreds of volunteers stationed across the UK and poised to help people who may be affected by possible flash flooding.
"Experience tells us that extreme weather could also lead to evacuations of homes and power cuts and we are ready to respond.
"We would urge people to keep a close eye on the forecast and think about preparing some basic emergency supplies in case the weather does take a turn for the worse."
Environment Agency flood risk manager Craig Woolhouse confirmed that further rain was expected. He said: "Heavy rain on Sunday may lead to localised surface water flooding in some parts of England and Wales.
"On Sunday and Monday a combination of high spring tides and strong westerly winds bring a risk of large waves and spray and possible flooding to the South West coast of England and along the Severn Estuary.
"If you're travelling to or from holiday then check your flood risk before setting off and don't drive through flood waters."
In Yorkshire drivers had to be rescued from their cars after rising water trapped them on roads.
Fire crew commander Paul Boon, based in Castleford, said lightning struck a house which caused internal wiring to catch fire.
Road flooded again in East Walton
Watch out pic.twitter.com/sNnUMM3yjq— rosie reynolds (@rosiere25082050) August 8, 2014
"The main bulk of the rain came down in half an hour to an hour," he said. "The amount of water in such a short time meant the drains could not cope and the police had to shut some roads. The water was up to our thighs, it was around 3ft deep, in some places."
In Cambridgeshire police inspector Kate Firman said ten people had been evacuated in March, but they are all back at home now.
She said: "The cleanup is now under way and we are doing what we can to mop up, so to speak. But we are bracing ourselves for potential further flooding tomorrow."
She said Cambridgeshire Police are reviewing their staffing levels to see if they need to enlist extra staff to cope with the fallout from the flooding.
The Highways Agency, police and fire and rescue services are today holding meetings to plan their response to flooding expected tomorrow.
A spokesman for UK Power Networks, which distributes electricity, said: "The first high-voltage fault happened at about 2.45pm yesterday with two more later in the afternoon, affecting more than 1,400 customers. Our engineers carried out repairs as quickly and as safely as possible, using alternative electricity circuits to restore supplies. The final two customers had supplies again at 2am today.
"We realise how difficult it can be to lose power and would like to apologise for the inconvenience caused by these incidents."
The flooding comes as many firefighters across Britain go on strike in a continuing row over pensions and working hours.
Norfolk's chief fire officer Nigel Williams is appealing for people to be vigilant during the walkout.
He said: "With some heavy rain forecast I recommend that people take extra care around any floodwater. Therefore, I would ask people to be extra vigilant during the strike periods as we have fewer firefighters available to deal with incidents.
"However, I would like to reassure Norfolk's residents that we have once again been working hard to ensure we have cover across the county and are as prepared as possible to deal with as many incidents as we can. We will prioritise the calls as they come in and we will do our best to protect the people of Norfolk."