Met Office forecasters have issued a yellow warning for thunderstorms in Hertfordshire.
The warning is in place over most of Great Britain and Northern Ireland, excluding the northern part of Scotland, today (Monday, August 15), tomorrow (Tuesday, August 16) and Wednesday, August 17.
Along with thunderstorms, meteorologists believe the UK is set to experience torrential downpours, which could lead to sudden flooding and potential road closures after dry conditions for more than one month.
According to the Met Office, homes and businesses "could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds".
Trains and buses could also be cancelled as a result of flooding and lighting strikes.
There is a "slight chance" of power cuts and the loss of other services to residential areas.
A spokesperson for the Met Office said: "Already some showers to start the day, but these likely to become more widespread and heavier through the late morning and afternoon, lasting into the evening in places.
"Some counties are likely to miss the worst of these storms but where they do occur, slow-moving torrential downpours could produce 20-30mm inside an hour, with 40-50mm falling in around two-to-three hours in a few spots.
"Hail and frequent lightning could pose additional hazards for some."
By Wednesday, the stormy weather is likely to have eased in most parts of the country.
Hertfordshire, Essex and Suffolk will remain under a yellow warning in the East of England.
London, the South East and the South West are also likely to experience storms into Wednesday.
The storm warning follows a period of "extreme heat" for the nation, with temperatures consistently topping 30C.
July 2022 was the driest since 1935 according to Met Office observers, while the Hertfordshire heat record was broken in Buntingford, East Herts on Tuesday, July 19 - the mercury hit 39.2C, beating the previous 37.9C record set at Aldenham, near Watford on August 10, 2003.
Firefighters have responded to the arid conditions by supporting a "league of extraordinary farmers" partnership.
Farmers in rural Hertfordshire can buy approved adapters for water pipes so fire crews can access a steady supply of water in rural locations, if they need it.
Jo Whitaker, people and wildlife officer at Panshanger Park, between Welwyn Garden City and Hertford, said wildlife is "struggling" as a result of the dry weather.
She said: "These prolonged dry temperatures are now very noticeable in our local green, or more accurately yellow, spaces.
"Panshanger Park has been suffering from the lack of rain. The grassland areas are dry and brittle with very little recent growth.
"This is to such an extent that the longhorn cattle have been given some hay to supplement their diet as the grass isn’t currently providing enough nutrition for them.
"The arid conditions across many of our habitats mean that our wildlife may be struggling too, so if you have a garden and are able to make some water available for wildlife please do."
Hertfordshire County Council's highways team is urging residents to be aware of the flood risk associated with storms.
A spokesperson said: "There is a weather warning in place for thunderstorms in Hertfordshire from August 15 to August 17, with a chance of heavy showers that could cause disruption or flooding.
"Please make sure to take care and allow extra time for journeys if you must travel."
Official observations show highs of 32C at Met Office stations in Bedford and London Heathrow Airport.
Slightly lower temperatures are forecast today, with highs of around 29C in Hertfordshire - cooling to around 25C at around 7pm when storms are due t hit.
Tomorrow (August 16) is set to be cooler still with highs of 24C in the northern part of the county.
Wednesday's highs are forecast at 21C.
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