The Met Office issues overnight yellow rain warnings on Wednesday and Thursday.
Heavy rain and strong winds are blowing through southern England as the storm approaches from France.
The Met Office has issued a yellow rain warning for most areas overnight and through Thursday – meaning people living there could see transport delays, flooding and power issues.
It comes in the form of a low pressure system named Storm Auror France, which brings 50 mm of rain and 45 mph winds to the most affected areas.
People were already posting the dramatic photos online late Wednesday.
Met Office forecaster Becky Mitchell told the PA news agency: “We have received warnings of yellow rain, which will last through the remainder of Wednesday at 3 a.m., covering the southern counties and the Channel Islands.
“The areas covered under the warning will see heavy and continuous rain, mostly between 15-25 mm, but at some places, thunderstorms can be expected to be 30 mm or more.
“Very strong winds are also likely, usually around 45mph on the coasts, reaching 70mph in the Channel Islands.
“This could cause some disruption to commuters tomorrow morning, as there could be flooding in some places – while there could be power outages due to the effects of thunder.”
However, the rest of the UK is likely to remain unaffected and will instead be “really cold”, with parts of Scotland falling below 0C due to a cold front from the north.
The Met Office says unstable weather is likely to continue for the rest of the week, with rain and wind conditions in western Scotland and some areas of central and northern England and Wales on Friday.
With the heaviest rain expected in western Scotland, forecasters have forecast more continuous rain over the weekend, with 40-60 mm of fall expected in 24 hours.
Northern Ireland, northern England and Wales may receive up to 20 mm of rain in six hours, while the southern and central regions will receive light rain.