The Environment Agency is warning that the next 48 hours are "crucial" after severe weather struck much of England and Wales.
Storms and threats of flooding have caused disruption and river levels have begun to rise.
A repeat of July 2007's devastation is feared after rain began lashing western England on Monday night.
Severe gales have hit much of west and south-east England and the Environment Agency has issued 82 flood warnings.
Bands of bad weather swept across much of the country during Monday night.
In Wales and the West Midlands 30mm (1.2in) of rain fell. The wettest place was Milford Haven in Wales where 33mm (1.3in) of rain fell.
Cornwall was battered by severe gales and heavy rain and the same is predicted for south-east England and East Anglia on Tuesday night.
A spokesman for the Environment Agency said: "It seems that Wales and the West Midlands is getting the worst weather but we should make it clear that it is currently nowhere near the scale of last summer, when there were more than 100 flood warnings.
"The problems will continue throughout the week. The next few days will be crucial."
Chris Fawkes from the BBC weather centre said that the rain had left much of the ground saturated - and although Wednesday was expected to be dry, further storms on Thursday could result in further floods.
"Today's rain won't drain through the system, so we could be looking at a very similar situation [to today], and there may well be more flooding," he said.
Flood warnings have been issued along the River Severn between Worcester and Tewkesbury, and from Tewkesbury to upstream of Gloucester.
The BBC's Jon Kay said while the flooding was not as severe as last summer, residents in Tewkesbury were still feeling anxious, particularly as more rain has been predicted.
He added the level of the River Severn was not expected to peak until Wednesday afternoon.
Kate Nelmes of Gloucestershire Police said: "We're not expecting things to be as serious as last year but we want to make sure we're prepared in case things get worse."
A force spokeswoman added: "There has been no need to carry out any evacuations at this stage, and it is anticipated that this situation will not arise.
"Gloucestershire Highways has reserve stocks of sandbags and have regular patrols throughout the county to monitor the situation."
In Upton-upon-Severn, Worcestershire, which was badly affected during the summer floods, the river has burst its banks, but defences have prevented it flooding the town centre.
Sgt John Roberts of West Mercia Police warned drivers in Worcestershire, Herefordshire and Shropshire that flooding on the roads was likely.
He added: "If you come across a flooded road, do not attempt to cross it as you cannot judge how deep the water will get and what hidden hazards may be under the water."
In Wales the flood plain of Pontcanna in Cardiff, north-west of the city centre, has been deluged by water, but the Environment Agency described this as "normal".
So far there are no reports of property flooding in Wales, the spokesman added.
Disruption caused by the weather has included:
Strong winds in the Channel Islands leading to delays on all flights between Jersey, Guernsey and Alderney
Train services cancelled in Hampshire, after flooding in the Botley and New Milton area
Some train services between Cheltenham and London Paddington delayed by flooding at Swindon
Traffic forced to slow down along the M5 after heavy rain, in particular between junctions 11 and 12 northbound.
Gloucestershire County Council highway teams have been clearing debris from roads and inspecting the conditions of the region's highways.
More than 4,000 homes and 500 businesses across Gloucestershire were affected by last year's floods.
Kelly Bartlett, of the Longlevens Flood Committee in Gloucester, one of the city's worst-affected wards, said the council had begun last-ditch efforts to widen and deepen the brook which runs through her area and residents were busy lining the streets with sandbags.
"Everyone in this area has stayed at home, no one has gone to work. You can't live a normal life. Every time it rains, you have to stay at home.
"People have moved their belongings upstairs."
Many flood warnings have remained in place since Friday, when flash flooding brought roads and railways to a standstill.
The agency said it expected the number of flood warnings to increase as the bad weather crossed Britain.
A spokeswoman said people in areas where warnings are in place should take action against potential flooding of homes and businesses.
The agency advised people to continually check the flood information section of the Environment Agency website, which is updated every 15 minutes.
FLOODING IN ENGLAND AND WALES
At 2300 there were 82 flood warnings and 184 flood watches in place
1: Worcestershire Barriers in place in Upton-upon-Severn after river burst its banks
2: Gloucs/Wilts Trains cancelled after flooding near Swindon
3: Wales Homes flooded in Abergavenny; woman rescued from car near Crymych, Pembrokeshire; roads flooded in Monmouthshire, Pembrokeshire and Swansea
4: Hampshire/Dorset Train services disrupted after flooding in Botley and New Milton
5: Channel Islands Delays to flights between Jersey, Guernsey and Alderney because of strong winds
6: Herefordshire River Wye expected to rise more than 4.5m above normal; roads closed because of flooding
7: West Sussex: Woman and three children rescued from flood-hit car in Lodsworth, near Petworth
8: East Sussex: Train delays after tree falls on line near Polegate
9: Kent: Shops and offices suffer flooding in Tonbridge and Great Chart, near Ashford; strong winds force temporary closure of Port of Dover to shipping