Storm Conall has brought heavy rain to parts of southeast England, triggering flooding that has blocked key rail lines.
Commuters are being warned of "severe disruption" on some parts of the network.
The Met Office predicted the third named storm of the season could bring up to 50mm (two inches) of rain on Wednesday - just days after torrential rain from Storm Bert over the weekend.
The highest rainfall was recorded on the Isle of Wight with 43.3mm (1.7in) in a 24-hour period until 10am.
The storm is forecast to deepen further to bring strong winds across the Netherlands later on Wednesday and into Thursday.
Get the five-day forecast where you are
A Met Office yellow rain warning had covered southern England, including Kent, Sussex, Surrey, Essex, Hampshire, Dorset, parts of London and the Isle of Wight.
A previous warning around Plymouth in Devon was lifted early on Wednesday morning.
Between 15 and 20mm of rain had been forecast, with 30 to 40mm in some areas and a lower chance of 50mm in parts of the South East, the Met Office said.
Disruption to rail routes
Flooding and other incidents have affected several train operators across the region because of Storm Conall including Thameslink, Gatwick Express, Great Northern, South Western and Southern.
National Rail is warning of "severe disruption" on parts of the network.
Thameslink said there are long delays or reduced services on routes in and out of London to St Albans, Sutton, Bedford and Brighton. Trains are suspended between Cambridge and Brighton.
Tunnels at Farringdon and Bletchingley both flooded.
Meanwhile Southern has suspended Gatwick Express services. There are also no trains running between Redhill and Tonbridge.
Great Western and South Western are reporting delays to services travelling through the Southampton area because of flooding and a fallen tree. It is affecting journeys to and from Cardiff Central, Bristol Temple Meads, London Waterloo and Portsmouth.
There are also problems between Guildford and Wokingham / Farnham. Trains are expected to be cancelled or delayed until 6pm.
On the Isle of Wight, services are affected between Ryde Esplanade and Ryde St Johns Road.
On Wednesday afternoon there were more than 80 flood warnings and nearly 160 flood alerts in place in England.
A severe flood warning, meaning there is danger to life, was still in place at Billing Aquadrome holiday park and the surrounding parks next to the River Nene in Northampton.
Storm Bert clean up continues
The heavy rain comes as communities are still clearing up after Storm Bert, which brought torrential rain and winds of more than 80mph, turning roads into rivers and flooding hundreds of homes.
Earlier, the Met Office warned more flooding is "likely" to hit the UK this week, with further potentially heavy rain arriving across southern areas alongside colder temperatures on Wednesday.
Chris Wilding, of the Environment Agency, said "significant flooding impacts" are probable in parts of Northamptonshire, with "minor" flooding on the River Severn.
Flooding impacts are not expected to worsen in Yorkshire and the West Midlands over the next few days.
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The naming of storms is shared by the KNMI, the Met Office and Ireland's Met Eireann to make communication of severe weather easier.
First launched in 2015, the storms list generally runs from early September until late August the following year, coinciding with the beginning of autumn.
(c) Sky News 2024: Storm Conall brings flooding and severe travel disruption, closing rail lines