Video report by ITV News Correspondent Paul Davies
Dramatic thunderstorms and torrential rain caused flash flooding across southern parts of England after a month's rain fell in just a few hours.
Amber flood warnings are in place across London and south-east of England, according to the Met Office.
Schools have also had to close due to the downpours while train stations have been flooded causing travel chaos.
Energy provider SSE said 1,273 homes across Basingstoke, Newbury, Reading and Bournemouth were left without power as a result of lightning.
Pictures on social media show severely waterlogged rail stations, platforms and stairwells at Didcot Parkway, Newbury and Chieveley stations across Oxfordshire.
South West Trains said as a result of the bad weather "several incidents are disrupting" the network.
A spokesman said: "A lightning strike has caused substantial damage to certain elements of our signalling equipment on the line which runs between Ascot and Guildford via Aldershot.
"Train services running through these stations may be delayed or revised. Disruption is expected until the end of the day."
Gade Valley Junior Mixed Infant and Nursery School in Hemel Hampstead, Hertfordshire, said on its website: "School is closed today due to severe flooding in the school."
While All Saints Church of England Primary School in Didcot, Oxfordshire, said: "The school will be closed all day to day due to flooding in Tamar Way resulting in access and drainage problems. We will re-open on Monday."
Met Office meteorologist Martin Combe said 32.8mm of rain had fallen in just three hours in Farnborough, Hampshire - nearly half the 70mm average for September.
He said: "The showers and thunderstorms are going to carry on for quite some time moving slowly north and eastwards, remaining around London through the morning and all afternoon in East Anglia."
Videos and pictures were shared on social media of dramatic electric storms across the UK.
Surrey Fire and Rescue Service said it had been called to reports of a house struck by lightning in Bracknell near Woking, while crews worked to pump water out of flooded premises across the county.
A train [**derailed near Watford Junction**](http://A train has derailed near Watford Junction causing major disruption to services in and out of London Euston station.) believed to be caused by a landslip causing major disruption to services in and out of London Euston station.
Fire crews were also called to rescue a man from a car stuck in flood water under a railway bridge on Portsmouth Road in Godalming at around 6.40am.
They also attended a fire caused by lightning that struck a row of six garages on Beechwood Road in Knaphill at around 9.30am. Two motorbikes were damaged, and no-one was hurt in the blaze.
Severe disruption was reported on the M4 at A34 and pictures emerged of Maidenhead High Street resembling a swimming pool.
A Thames Valley Police spokesman said: "Roads are severely disrupted, including the M4 at the A34 junction with Newbury, the M40 throughout the Thames Valley and in particular the Watlington and Stokenchurch area."
The weather front is due to send temperatures tumbling ahead of the weekend, just days after parts of the country baked in 34C (93F) heat.
A narrow corridor west of London is expected to be hit by "exceptionally heavy, thundery rain" accompanied by hail on Friday, the Met Office said.
Turnpike Lane and Manor House on the Piccadilly line were closed early on Friday but re-opened around 6.20am, Transport for London (TfL) said.
Away from the storms, Friday will be a relatively cool and fresh day for most of the country with some sunshine.
London is expected to see a high of 21C (70F), Cardiff 18C (64F) and Manchester, Glasgow and Belfast 17C (63F).