Large swathes of Britain to be lashed by thundery downpours as Met Office issues three new warnings - as UK braces for flooding and travel chaos

Huge swathes of the UK are expected to be drenched in thundery downpours at the Met Office issue stark new warnings to brace for flooding and travel chaos.

Wet and stormy weather is expected across South West England and South Wales with a 'danger to life' warning issued.

Britons should expect possible flooding, power cuts and travel disruption in Bangor, Cardiff and even Liverpool throughout the day.

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. 

A yellow weather warning which includes travel disruption, flooding and power cuts has been issued as thundery downpours are expected across southern England

A yellow weather warning which includes travel disruption, flooding and power cuts has been issued as thundery downpours are expected across southern England 

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 and extending up to Liverpool

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 and extending up to Liverpool 

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

'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.'

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.'

the wet forecast follows a soggy seven months so far which has seen rain derail stay-cation summer plans for many.

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

Summer plans have been derailed for many due to the constant wet weather. Pictured: Tennis-lovers sheltering under umbrellas, watching Wimbledon on the Hill

Summer plans have been derailed for many due to the constant wet weather. Pictured: Tennis-lovers sheltering under umbrellas, watching Wimbledon on the Hill

Stay-cations and weekends away have been scuppered by a wet start to the year which is set to continue this week. Pictured: Tourists huddling under umbrellas while punting along the River Cam in Cambridge

Stay-cations and weekends away have been scuppered by a wet start to the year which is set to continue this week. Pictured: Tourists huddling under umbrellas while punting along the River Cam in Cambridge

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.'

The Met Office has warned home owners caught in the deluge to make plans and secure their homes in the event of flooding. 

They have advised drivers to check conditions before setting out and choose the safest route but to be aware of possible disruption.