Thunderstorms are set to strike much of the UK on Saturday, forecasters have warned.
The Met Office has issued a yellow warning for heavy showers and thunder which could cause flooding, power cuts and travel disruption in England, Wales and Northern Ireland.
The warning covers large expanses of the three nations, with the exception of some coastal areas, and lasts from midday until 10pm on Saturday.
Met Office forecaster Greg Dewhurst said up to 40mm (1.6in) of rain is expected to deluge the areas covered by the yellow warnings on Saturday.
He said: “On Saturday we will see a band of heavy rain push north-eastwards across the UK, followed by sunshine and heavy showers.
“Sunday will see the heavy rain clearing to bright and sunny spells and heavy showers in the east.”
This comes after areas including London have already seen a month’s worth of average rainfall for August with 12 days still to go.
Mr Dewhurst said City of London has had 117% of its usual August rainfall already, with 60mm (2.4in) of rain falling on the capital up to August 19, compared with 51mm (2in) usually seen over the entire month.
Northern Ireland has had 91mm (3.6in) of rain – 93% of its 97mm (3.8in) average for the month.
Meanwhile, other areas have been exceptionally dry, including North Yorkshire which has had less than 50% of its usual rainfall.
Mr Dewhurst said overall UK temperatures and rainfall for the time of year are “about average”.
On Saturday, the mercury is set to rise to around 21C in London, 20C in Cardiff, and 18C in Edinburgh and Belfast.
Localised heavy rain and hail has already caused “significant problems” for harvests, according to the National Farmers Union (NFU).
A spokesperson for the union said this year’s harvest was delayed due to cold spring temperatures, but it is too early to say how much profits will be impacted and whether consumers could see a rise in food prices.
They said: “The localised heavy rain and hail has caused significant problems in certain areas.
“It’s a mixed picture because for many areas they just haven’t had many clear dry days in a row to harvest, so things have been a bit ‘stop-start’ with harvesting.
“Where they have been harvesting, grain has often had to be dried because the better weather hasn’t lasted long enough to get moisture levels down to where they need to be.
“The problems will grow if the unsettled weather continues because it will start to impact on the quality of the grain if it goes on too long, especially for crops like milling wheat.”