BBC Weather forecaster Sarah Keith-Lucas warned BBC Breakfast viewers large hail and flash flooding could be expected as a result of relentless thunderstorms hitting the UK in the next 48 hours. She said: “The heaviest of thunderstorms look to be easing in the east of Scotland but there could be some heavy ones cropping up further south across parts of Scotland, England and Wales. Northern Ireland looking mostly dry through the day.
“Temperatures could be slightly lower than recent days, around about 32C or so. But one or two spots could see the temperatures again today up to about 34C. So another hot day.
“As we head on into the evening hours we’ll start to see more of those heavy showers and thunderstorms, particularly across parts of southern England and Wales as we move overnight and into tomorrow morning.”
She added: “Heading through tomorrow it looks like eventually something slightly cooler is on the cards but it is still quite a humid day.
“With further heavy showers and thunderstorms especially across parts of southern England tomorrow and Wales as well.
“So expect some flash flooding and possibly some large hail as well.”
The Met Office has upgraded its weather warnings for the region from yellow to an amber alert.
In a statement on its website, the Met Office warned that the East of Scotland was be battered with thundery showers overnight.
They added: “Thundery showers are likely to gradually move northwards overnight with continuing areas of torrential rain, frequent lightning and hail as well as perhaps gusty winds.
“Where the storms become heaviest and most prolonged rainfall totals of 30-40 mm could fall in an hour with some places potentially receiving 60-80 mm in 3 to 6 hours, although only a few sites will see these totals with perhaps parts of Fife seeing these early in the night and the far northeast on Wednesday morning.”
“Power cuts may occur and other services to some homes and businesses could be lost.”
The thundery rain should mostly clear out from Scotland by midday, but for the rest of the UK thunderstorms could crop up by the evening.
A yellow warning for thunderstorms and flooding has been issued by the Met Office for nearly all of the UK, excluding West Scotland and Northern Ireland.
Temperatures will remain as high as 32C (89.6F) around 5pm in London and much of the South East.
For the morning it will remain clear and sunny, but after midday intermittent thunderstorms could breakout as the heatwave begins to falter.
Wales and the West of England will see marginally cooler temperatures of around 27C (80.6F), but northern winds will bring a clash with the plume of heat, making thunderstorms and showers much more likely in these areas.