Torrential rain threatens to bring widespread floods, power cuts and travel chaos on Tuesday, the Met Office warns.
A further 89 alerts have been issued for areas where flooding is possible. Gusts of up to 35mph and milder-than-average temperatures are the result of a low-pressure vortex to the west caused by the recent big freeze in North America.
London is expected to escape the worst of the flooding but heavy rain is expected throughout Tuesday.
Wednesday will be brighter but colder and more windy in the capital, with some sunny spells and scattered blustery showers.
Local groundwater flooding is possible through the next five days in the south of England, forecasters have warned.
Up to 80mm of rain could fall in Cumbria, forecasters fear.
Flood barriers have been put up in Ironbridge and Shrewsbury in Shropshire and Bewdley in Worcestershire in an attempt to stop the River Severn bursting its banks.
"Frequent and sometimes persistent bands of rain across Wales and the Upper Severn area have resulted in saturated and full catchments, raising river levels along the Severn," a spokesman for the Environment Agency said.
"Today local river and surface water flooding impacts are probable in parts of the North West and the Midlands, and possible more widely due to widespread heavy rain."
He said this level of rainfall was "not uncommon" for the time of year and could persist until the end of the week in the West Midlands and parts of the North East.
The Met Office has said “some disruption” is expected , including “flooding of a few homes and businesses”, “spray” on the roads, increased journey times on public transport, and “possible” power cuts.
Meteorologist Alex Deakin described the overall forecast for Tuesday as “a rather dull and damp affair” featuring “gusty winds”.
But he added that it will be “milder than Monday”, with temperatures in the double digits for much of the UK.
Mr Deakin said: “The rain will be spreading its way through eastern England and then through Scotland.
“There will be heavy and persistent rain for north-west England and parts of Wales, and, because it has been so wet recently, this extra rain could cause some issues, so we do have Met Office yellow warnings in place.”
He added: “For many it will feel milder than Monday, but there is more wet and windy weather to come through the evening across Wales and western parts of England.
“Rapidly that band of rain should sweep across England and Wales, leaving clearer skies for a time but also plenty of showers coming in.”
More than 140 flood warnings have also been issued across Britain by environment regulators, because saturated ground caused by recent wet weather means that even areas which avoid the worst of Tuesday’s deluge could be at risk of flooding.
Natural Resources Wales has issued 20 flood alerts across the same areas covered by the Met Office warnings.
The Scottish Environment Protection Agency (Sepa) has issue five flood alerts across south-west Scotland, covering Argyll and Bute, Ayrshire and Arran, Central Scotland, Dumfries and Galloway, and West Central Scotland.