Thunderstorm warnings are in place for much of the UK as soaring temperatures could reach 31C (87.8F) on Saturday.
Forecasters said the rising heat could see the hottest day of 2023 so far but may also bring torrential rain, hail and gusty winds – and warned of “really balmy nights on the way” with temperatures in some areas likely to still be at 20C (68F) late into the evening.
Saturday’s scorching weather could mean the UK is hotter than Marrakech in Morocco, which could see highs of 29C.
But a yellow thunderstorm warning – highlighting the possibility of localised flooding and the potential for disruption to travel and power supplies – has been issued for Wales and a large part of southern and central England from 2pm to 9pm.
Another yellow warning is in place on Sunday from midday to 9pm for Wales, Northern Ireland and most of western and central England and Scotland.
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The UK Health Security Agency (UKHSA) has issued an amber heat-health alert for hot weather until 9am on Tuesday in the West Midlands, East Midlands, East of England, South East and South West.
It means the impact of the heat is “likely to be felt across the whole health service… and the wider population, not just the most vulnerable”.
Met Office chief meteorologist Frank Saunders said: “As the heat builds from the South, thundery showers will develop through Saturday afternoon.
“While not everyone in the warning area will see the heaviest showers, or even any rain at all, some will bring heavy thundery downpours.
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“With intense showers there is a risk of surface water flooding which could cause some disruption.
“Sunday will see 30C (86F) again in parts of southern UK and the risk of thunderstorms more widely – particularly western and central areas.”
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Forecaster Tomasz Schafernaker added: “We will notice the humidity rising as we go through the weekend with some really balmy nights on the way.
“At 10pm on Saturday, temperatures in some towns and cities will still be hovering around 20C.
“For Sunday there’s a lot of sunshine around, very warm, very humid but with a greater chance of catching showers and thunderstorms across many western parts of the UK… hail, thunder and gusty winds and then it is back to sunshine again.”
