Thunderstorms to batter the UK with flash flooding, hail, lightning and half a month's worth of rain today (but there'll still be a hosepipe ban)

Daily Mail​

21-07-2025

Most of Britain was on thunderstorm watch today as up to half a month's rain could fall with forecasters warning summer storms are set to bring flash flooding.
England and Scotland could see up to 40mm (1.6in) of rain in just two hours, while Northern Ireland will be worst hit where 75mm (3in) may accumulate in 18 hours.
It comes as the third major hosepipe ban of summer began today, with Southern Water activating restrictions for households in Hampshire and the Isle of Wight.
This follows a ban from South East Water in Kent and Sussex since last Friday, and in the Yorkshire Water area since July 11. A fourth ban from Thames Water begins tomorrow in Oxfordshire, Gloucestershire, most of Wiltshire and parts of Berkshire.
Despite three consecutive days of heavy rain, forecasters say this will do little to replenish groundwater reserves because it is running off very dry surfaces too fast to penetrate – and therefore the downpours are not enough to lift hosepipe bans.
Yorkshire Water confirmed its restrictions will only be lifted when 'reservoir and groundwater levels return to where we need them to be', adding that the region would require 'a few months of wet weather rather than intermittent rainfall'.
Parts of the UK will experience heavy, thundery downpours today, with an amber weather warning for rain in place until 8am for the east of Northern Ireland.
Met Office forecaster Simon Partridge, said: 'It looks like Northern Ireland is the place where we could see the most rainfall and certainly the most impactful rainfall.
'They could see 50 to 75mm of rain within 12 to 18 hours.'
The country records an average of 89mm of rain in July, meaning more than half a month's rainfall could hit Northern Ireland in less than a day.
Forecasters have warned of a risk of flash flooding in County Antrim, Armagh and Down as the heavy showers are set to batter the country.
Meanwhile, parts of England and Scotland could see 20mm to 40mm of rain in just two hours today.
From 3am until 9pm today, the South and East of England are covered by a yellow thunderstorm warning.
By 11am the same warning will be in place for the Midlands, northern England and Scotland.
More than 11 flood alerts remain active in England and 15 in Scotland.
Where there is flooding or lightning, the Met Office has warned of a chance of delays and some cancellations to trains and buses.
There is also a small chance of power cuts and of fast-flowing or deep floodwater causing danger to life.
'We could see some locally heavy downpours, 20 to 40mm of rain is possible in a couple of hours,' Mr Partridge said.
'That is potentially up to around half a month's worth of rain in a couple of hours in some places.
'You will see quite a lot of water on the roads and difficult driving conditions.
'Hopefully nothing more significant than that, it certainly won't be an issue for any of the rivers because they are quite low.'
Low pressure and humid, moist air across the country will cause the heavy, thundery showers, but even within the warning areas some places will stay dry, the Met Office said.
'There is a good chance of seeing some lightning and some hail, with some gusty winds as well,' Mr Partridge said.
The rest of the week is set to be changeable, with showers likely tomorrow and thundery downpours possible in the South East of England on Wednesday.
Temperatures this week will be around average for the time of year.
The wet weather comes after a dry and hot spring and three heatwaves so far this summer which left four regions of England in drought.
England recorded its driest March to June period since 1893, according to the Environment Agency, and dry ground can make flooding more likely as it is unable absorb as much water.
Today, Southern Water became the latest company to activate a hosepipe ban, to protect rare chalk stream habitat in response to the driest start to the year since 1976 for England.
The company said restrictions were being imposed on hosepipes for activities such as watering gardens, filling paddling pools or washing cars.
The move aims to protect the Test and Itchen chalk streams, which supply most of the area's water, but are at 'critically low levels', down 24% on normal flows for the time of year, Southern Water said.
Rainfall across England was 20 per cent less than the long-term average for June, which was also the hottest on record for the country, with two heatwaves driving unusually high demand for water, the Environment Agency has said.
Drought was declared in East and West Midlands last Tuesday, with the region joining swathes of northern England in drought status.
Southern Water's water managing director Tim McMahon said: 'We're sorry we're taking this step, but as other water companies have already done, we have to respond to the widespread and prolonged dry weather affecting our region.
'In our case, this means a hosepipe ban for our customers in Hampshire and the Isle of Wight to protect the health of our amazing chalk streams, which as one of the rarest habitats on earth has been compared to the Amazon Rainforest.
'We must act now to support the wildlife that live there, including Atlantic salmon and southern damselfly.'
He said the company has been working '24/7' to find and fix leaks, and ensuring the network is working as efficiently as possible, but it is 'not enough', and he urged customers to help to reduce use by adhering to the ban.