The Met Office has warned Londoners of possible thunderstorms on Thursday as commuters faced an extremely soggy morning rush hour.
Heavy rain was battering the capital as thousands in the capital made their way to work, carrying the risk of flash flooding and lightning strike damage.
It comes after the UK registered its hottest and sunniest spring since records began in 1884, and driest for half a century.
Those travelling in and out of the city faced a wet journey to work and school, with a 95 per cent chance of “heavy rain” from 7am until 9am.
Bus and rail services could also be impacted by the unsettled conditions, with gusts of up to 30mph (48kph) predicted by forecasters.
On Friday night, a new weather front will bring showers, which potentially could be thundery at times on Saturday.
Commuters and walkers are advised to carry wet weather gear, particularly in the afternoon, despite intermittent sunny spells.
Rainfall will be seen across all areas of Britain at some point this week, with a continuation of cooler and "a bit breezy" weather.
Andrea Bishop, a Met Office spokesman, added there could be up to 30mm (1.2ins) of rain in some parts of southern England.
However, temperatures look to remain cool in the mid- to high-teens and high pollen levels are set to continue.
The mercury is expected to rise to just above average for the time of year, with highs of 24C (75F) next Wednesday.
Generally, the theme is the continuation of something a bit cooler, a bit breezy at times, and a bit wet at times too
Ms Bishop said: "The weather will be changeable for the rest of this week, with everyone likely to see some showers at some point.
"Generally, the theme is the continuation of something a bit cooler, a bit breezy at times, and a bit wet at times too.
"We are keeping an eye on a new front which looks like it will move in on Friday night, bringing rain which could be heavy, and possibly thundery at times on Saturday.
"Rainfall totals of 20-30mm are likely in places and at present, this looks like it will affect the southern half of the UK.
“We are keeping a close eye on this to see how it evolves over the next 24 hours or so."
