Hailstorms the size of cricket balls are set to smash into Britain this weekend[NETWEATHER/GETTY]
The UK is about to be rocked by the most frenzied and chaotic start to summer EVER as monsoons and tornadoes rage in.
Ice stones the 'size of cricket balls' will cause devastation across the country in what forecasters fear could be the the worst hailstorms since a deadly 'supercell' led to hailstones leaving craters FIVE FEET deep across England 171 years ago.
Temperatures are expected to rocket to an incredible 91F (32.6C) by Saturday as a swathe of roasting hot air suddenly floods the British Isles.
Heavy and persistent downpours will start today with parts of the south on alert for extreme flash floods.
But the really dramatic weather will start on Friday night when two 'battling' weather systems will fight it out over Britain.
The resulting carnage will trigger tornadoes and fierce winds, enormous hailstorms and potentially DEADLY lightning strikes.
The Met Office has issued a severe weather warning across virtually the entire country on Saturday and warned of major travel disruption.
Huge thunderstorms, lighting and hail is forecast for much of Britain this weekend [GETTY]
The warnings come as the latest weather forecasting models predicted a huge plume of warm air will sweep into the UK from the continent on Friday triggering the extreme weather.
Met Office Chief Forecaster Frank Saunders said: “Thundery downpours are expected to affect parts of England, Wales and southern counties of Scotland during Saturday.
"The public should be aware of the potential for localised flooding due to the intensity of these storms, although at this stage the location of the heaviest rainfall is uncertain.
"Warm, humid air is likely to be pulled northwards from France late on Friday and during Saturday.
"Within this airmass, there is an increasing likelihood that heavy, thundery showers will break out."
The volatile conditions are being driven by an area of high pressure from the continent and low pressure from the Atlantic crashing over the UK.
Jonathan Powell, forecaster for Vantage Weather Services, said ferocious storms, rain and winds cold last until the end of next week.
He said raging temperatures will trigger "spectacular" thunderstorms while colliding air masses will trigger 'extreme tornado activity' in parts of Britain.
He said: "We are expecting a crescendo of heat on Friday and into Saturday and this is expected to trigger violent, almost tropical storms across the country.
"It is possible we could see hailstones the size of cricket balls.
"There is also a risk of severe tornadoes which are whipped up when two weather fronts battle it out, as we are expecting.
"There is the added ingredient of warm air being sucked in from the continent on Friday, and this could be the picture through next week."
Some of the biggest hailstones ever recorded could fall in Britain in the coming days [GETTY]
A crescendo of heat will trigger violent, almost tropical storms across Britain. We could see hailstones the size of cricket balls.
Jonathan Powell, forecaster for Vantage Weather Services
He warned the south to expect the most violent thunderstorms although most of the country should batten down the hatches for extreme conditions.
Netweather said with extreme humidity, temperatures could feel as high as 91F in the south as a plume of hot air approaches the UK.
Forecaster Paul Michaelwaite said: "As we move into the latter part of the week and the first part of the weekend there are some question marks currently as the plume of warmer air may slide further east and miss the UK, but it does look likely that temperatures will be on the rise.
"That is only part of the story though with the risk of some heavy rain and thunderstorms moving up from the south too."
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Leon Brown, forecaster for The Weather Channel, said more than an inch of rain could fall in parts with Saturday likely to be the hottest day of the year so far.
He said: "The weekend begins to become quite unstable from the west with some heavy and thundery downpours moving across the west on Saturday morning and then to central and eastern areas on Saturday afternoon to evening.
"There is a risk of local flash floods with 20 to 30mm [1.2ins] falling in short periods, temperatures will rise sharply and it is going to feel humid.
"Next week looks like starting very warm and humid again with more heavy and thundery downpours moving up from the southwest."
The Environment Agency has four flood alerts in place in the south east where river and groundwater levels remain high after the winter floods.
The areas still most at risk during heavy rain are near rivers in Berkshire, Hamphire and Basingstoke.
The shock forecast warns of spectacular thunderstorms, lightning and tornadoes [GETTY]
The worst hailstorm recorded in British history struck on August 9 1843 when a supercell caused enormous hailstorms to fall from the skies, resulting in huge craters and widespread injuries across central and southern England.
The massive storm also spawned destructive tornadoes and caused so much damage that a brand new insurance company - The General Hail Insurance Company - was formed to cope with the sheer volume of claims. The company later became known as Norwich Union.