Storm Bert is bringing further widespread disruption with public transport badly affected after “devastating” flooding over the weekend.
Several rail operators have cancelled services on Monday while more than 180 flood warnings remain in place.
Hundreds of homes were left under water, roads were turned into rivers and winds of more than 80mph were recorded across parts of the UK.
Two severe flood warnings, meaning there is danger to life, have been issued for the River Monnow in south-east Wales for Monmouth and Skenfrith, after a major incident was declared in the nearby Rhondda Cynon Taf region on Sunday.
In England, a severe flood warning has been issued for Billing Aquadrome and surrounding parks next to the River Nene in Northampton.
More than 150 flood warnings and more than 200 flood alerts have been issued by the Environment Agency in England, with a further 22 flood warnings and 36 flood alerts in place in Wales.
Rail passengers have been urged not to travel between Broxbourne, Hertfordshire, and Stansted Airport after multiple fallen trees damaged the electrical overhead wires, with no trains expected to run until 2pm.
London Northwestern Railway reported that no rail services would operate through Northampton station due to the River Nene bursting its banks.
Southern, which runs rail services across the south-east of England, said some services on Monday will be cancelled or revised because of forecast severe weather, including on its London network and the West Coastway between Havant and Southampton.
Great Western Railways warned passengers not to travel as it suspended services on all key routes because of flooding and fallen trees.
Transport for Wales said all services between Pontypridd and Treherbert, Aberdare and Merthyr Tydfil were currently cancelled with disruption expected throughout Monday.
It added lines were closed between Hereford and Abergavenny due to a landslip with no rail replacement service available, while no services would run between Shrewsbury and Swansea until at least 12pm.
Services between Lancaster and Barrow-in-Furness in Lancashire will not run until Friday due to heavy flooding, with rail replacement transport extending journey times by up to an hour.
Southwestern Railway said all lines between Fareham and Southampton Central had now opened after the removal of a tree, but services would be disrupted until 11am.
ScotRail advised customers speed restrictions would be in place on many of its routes leading to longer-than-normal journey times.
On the roads, the A5 is closed in both directions between the A508 and the junction with the A43 because of flooding as of Monday morning.
A lane on the A14 eastbound between junctions J16 Catworth and J18 Spaldwick West is also shut with disruption expected to clear between 8.45am and 9am.
The Met Office forecast that rain in the south-east of England will clear on Monday but blustery showers could stick around for the north-west.
All of the forecaster’s rain warnings ended on Sunday but strong winds persist and rain from high ground will reach rivers, which could disrupt clean-up efforts.
A yellow wind warning remains in place for much of central and western Scotland until 10am, with gusts of up to 70mph likely in exposed areas.
Around 350,000 homes in England lost power during the storm, though most have since been reconnected.
More than 300 flights set to depart from UK airports were cancelled during Storm Bert, aviation analytics firm Cirium said.
Some areas saw in excess of 130mm of rainfall in just 24 hours on Sunday.
