Floods hit properties, closed an M25 slip road and caused travel delays across the south east of England after a night of heavy rain. Flood warnings were issued for parts of East Sussex and Kent, with flooding expected until Friday morning.
At least 45 properties have flooded across Kent, the Home Counties, Hertfordshire and Bedfordshire, according to the Environment Agency.
Meanwhile, there have been train delays due to the "severe weather" affecting Gatwick Express, Southern and Thameslink services, Southern Railway said.
Drivers were asked to find alternative routes into London after National Highways said on X that the northbound entry slip road from the M25 at junction 10 (Guildford) was closed due to flooding.
Traffic monitoring site Inrix reported at 11:00 BST that the slip road had reopened.
The Met Office issued a yellow warning for rain from 05:00 until 23:59 on Monday across Kent, Surrey and Sussex.
A yellow warning for rain means some communities may be cut off by flooded roads, with possible power cuts and loss of other services to some homes and businesses, it said.
Flood warnings have been in place on Monday for the River Medway between Forest Row and Penshurst, along with the Rivers Eden and Eden Brook from Crowhurst to Penshurst.
There have been flood alerts for the River Rother and its tributaries from Turks Bridge to the Royal Military Canal, the lower and middle River Medway and around the River Bourne, from Hadlow to East Peckham in Kent.
Flood alerts were also issued for the Upper Ouse and River Adur in Sussex, plus the area around Gatwick Airport from 08:00, covering surrounding towns and villages including Charlwood, Hookwood, Crawley and Horley.
An airport spokesperson said there were no issues at Gatwick on Monday morning.
Surrey's River Mole and its tributaries from Kinnersley Manor to South Hersham were also subject to flood alerts.
Network Rail Kent and Sussex apologised to passengers for disruption to trains after flooding on the Hayes and Hastings lines.
In a post on X, Network Rail said: "At Wadhurst, the flooding has impacted signalling kit - the railway’s traffic lights - and we’ve got a flooded transformer which needs replacing.
At about 17:00, Southeastern said repairs had been "unsuccessful" and that a reduced service would run between Tunbridge Wells and Hastings until the end of the evening.
Issues with flooding at Lower Sydenham on the Hayes line have been cleared, Southeastern Railway said, and the line was running normally.
National Rail said there was earlier disruption on Gatwick Express, Southern and Thameslink services, while South Western Railway said lines had reopened following flooding at Walton-On-Thames.