UK weather forecast: Met Office warns people to 'stay out of sun' until weekend, with hottest day of decade possible

Outside chance that temperatures could top 36.7C – but the mercury will 'certainly' reach 34.5C

People are being warned to stay out the sun between now and the weekend, as forecasters said the UK’s hottest day of the decade could be on its way.

The Met Office issued an amber heatwave warning, advising people to stay in the shade, keep homes cool and shut windows during the day throughout the week.

“There is a 90 per cent probability of heatwave conditions between 9am on Monday and 9am on Friday,” it said in a statement, adding that southern and eastern parts of England were most likely to be effected.

Like much of the UK’s green space, Greenwich Park in London has browned in the heat. EPA (EPA)

The mercury may top 34.5C on Monday, Thursday and Friday, Met Office meteorologists say – which would beat both last year’s and 2016’s records highs.

But there is also an outside chance the warmest temperature registered this decade – 36.7C at Heathrow in July 2015 – could be put in the shade.

“There will be highs of 32C in the south east and East Anglia today with a chance of some areas reaching above 33C and 34C,” said forecaster Craig Snell. “But then, after fresher days on Tuesday and Wednesday, we certainly expect to get above 34.5C somewhere in the south east of England by Thursday and Friday.”

Asked if we could expect the hottest day of the decade, Mr Snell said: “There is a chance but it is a very low chance.”

Highland cows take a dip in Northumberland. SWNS (SWNS)

Most places will stay dry and humid throughout the week, he added, although there may be isolated showers in the north of England, Scotland and Northern Ireland.

And after a slightly cooler weekend, when temperatures will dip into the high 20s, the bake will be back next week.

Yarrow reservoir in Lancashire is far below capacity. SWNS (SWNS)

“It will stay warm but fresh over the weekend but the heat will then return next week with the east of the country in particular experiencing temperatures once again in the early 30s by Wednesday,” he said.

He forecast that the fine weather will remain into mid-August, although with possible occasional thunderstorms.

The warm weather is being pushed up from the equator and southern Europe by an Atlantic air front with the UK not the only country experiencing the heatwave. In the Netherlands and Belgium, the mercury is expected to reach a potential 39C this week.

Last year’s hottest UK temperatures was 34.5C recorded at Heathrow on 21 June. In 2016, it was 34.4C in Gravesend in September.