Rain on our parade! Hopes of summer are dampened yet again with huge downpours set to hit southern England and Wales in just hours - as the Met Office warns of flooding, power cuts and travel disruption

Huge downpours are set to hit southern England and Wales in a matter of hours this morning as the Met Office warns of flooding, power cuts and travel disruption.

A yellow weather warning for rain is in place from 8am today until 11.59pm for parts of England, including tourist hotspot Cornwall, and Wales with 'thundery downpours' forecast. 

Up to 40mm could fall within a three hour soaking that could cause power outages to homes, as well as trains and buses to be cancelled or delayed, the Met Office warned, as the summer washout misery continues. 

'Outbreaks of rain, some heavy and thundery, will spread steadily north across the area during Monday,' the Met Office said.

'Some torrential downpours are likely in places with 15 to 20mm falling in less than an hour and as much as 30 to 40 mm in three hours.

'This is likely to lead to localised flooding, slower travel times and a small chance that homes and businesses could be flooded.'

LONDON -- People shelter under their umbrellas in Westminster as the rain pours down on July 7

LONDON -- People shelter under their umbrellas in Westminster as the rain pours down on July 7

BERKSHIRE -- A van splashes through floodwater in Windsor after a night of torrential downpours on July 6

BERKSHIRE -- A van splashes through floodwater in Windsor after a night of torrential downpours on July 6

A yellow weather warning for rain is in place from 8am today until 11.59pm for parts of England, including tourist hotspot Cornwall, and Wales

A yellow weather warning for rain is in place from 8am today until 11.59pm for parts of England, including tourist hotspot Cornwall, and Wales

Up to 40mm could fall within a three hour soaking that could cause power outages to homes and trains and buses to be cancelled or delayed

Up to 40mm could fall within a three hour soaking that could cause power outages to homes and trains and buses to be cancelled or delayed

The warning covers Cheshire, Halton, Merseyside, and Warrington in north-west England, all of Wales, and Devon, Somerset, Bristol, and Cornwall in the south-west.

It's better news for those in the north with the mercury set to reach a cosy 21C in Manchester and York. 

On Tuesday, the weather will turn 'heavy and thundery', especially in the east. 

Outbreaks of rain and strong winds are forecast for Wednesday with it expected to be drier on Thursday afternoon and Friday.  

It comes after last week's deluge of thunderstorms, which saw people sheltering under their umbrellas in Cambridge and London, briefly came to a halt with a glimpse of the glorious summer sunshine. 

According to traditional folklore, the weather experienced on St Swithin's Day (July 15) will continue for the next 40 days - meaning parts of the country could be in for a wet rest of the summer if the superstition holds true.

The proverb of St Swithin says: 'St Swithin's Day if thou dost rain, for forty days it will remain, St Swithin's Day if thou be fair, for forty days will rain na mair.'

Tourists sheltering from the rain as they queue outside the Natural History Museum on July 9

Tourists sheltering from the rain as they queue outside the Natural History Museum on July 9

Shoppers on Oxford Street carry umbrellas to shelter from the rain last week

Shoppers on Oxford Street carry umbrellas to shelter from the rain last week

A taxi splashes through a large puddle as heavy rain drenched the capital on July 9

A taxi splashes through a large puddle as heavy rain drenched the capital on July 9

Grahame Madge, of the Met Office, has explained why the UK is currently experiencing a miserable summer.

He said: 'In a typical summer, the jet stream moves to the north of the UK, allowing areas of high pressure to develop in the meanders, bringing more settled and often warm weather.

'However, this summer the jet stream has been largely more south-shifted, meaning we are on the cold side of the jet.

'Areas of low pressure associated with the jet stream have also brought more unsettled conditions to influence, bringing bouts of wind and rain.

'This isn't an unprecedented weather picture for summer by any means, but this pattern looks as though it will remain in the forecast for some time to come.'