Thunder, lightning and heavy rain is set to lash large swathes of the UK on Father's Day
.A yellow Met Office weather warning for thunderstorms almost entirely covers England and Wales between noon and midnight on Sunday, and there is also one in place until 9pm in Northern Ireland.
It warns of heavy showers, with as much as 80mm falling within three to six hours in the worst affected regions.
There is also the potential for frequent lightning, strong winds and hail - which could cause flooding, travel issues and power cuts.
However, the heat will continue, with temperatures reaching the mid 20s and humid conditions being felt around the country.
Grahame Madge, for the Met Office, said: "Some of the storms have the potential to be quite intense, with high rainfall rates.
"Some locations may well miss them all together but all we can do now is indicate that there is a risk across both countries."
He added: "We will keep the yellow warning closely monitored and if we need to escalate that for local areas then we will."
Met Office Deputy Chief Meteorologist Chris Almond said: “Over the weekend we’ll be transitioning to a more unsettled regime for the UK, though temperatures will remain high and it’ll feel very humid for many.
“Heavy showers and thunderstorms are likely to become more frequent and impactful through the weekend, with the potential for associated hail, lightning and some gusty winds. The risk of thundery downpours initially starts in the far west on Friday afternoon, but spreads more widely through the weekend, resulting in the warning the Met Office has issued.
“There’s an ongoing likelihood of further warnings being issued and revised in the coming days, so keep an eye on the forecast for the latest outlook.”
Sarah Cook, of the Environment Agency, said: "On Sunday afternoon and into the night, slow-moving heavy showers and thunderstorms could lead to localised surface water flooding across England."Environment Agency teams are out on the ground and will support local authorities in responding to surface water flooding."
Met Office five-day forecast
Sunday:
Sunny spells and scattered showers at first. During the day showers will break out more widely, especially across England, Wales and Northern Ireland, turning very heavy and thundery in places.
Outlook for Monday to Wednesday:
Scotland will have outbreaks of rain on Monday, some heavy and thundery. Otherwise there will be a general mix of very warm sunshine and scattered showers, these perhaps still thundery.