Leigh Boobyer
Live reporter

Image source, PA Media

In Gloucestershire the annual cheese rolling races, which see competitors tripping and stumbling down an incredibly steep hill, do not usually take place in conditions this hot.

BBC reporter Andy Howard says he can recall the races down Cooper’s Hill taking place in drizzle, heavy rain and in very cold conditions, but never in temperatures this warm.

Ahead of today's races, the hill was described as very firm, with plenty of stones – not great conditions for the competitors who brave injury in their pursuit of the large double Gloucester cheese which is sent down the hill to signal the start of each race.

For the spectators too it has been a challenging day, with people getting there early to find the few shady spots to watch the race from.

• For more on the dash for cheese, check out the BBC's local coverage

As we've been reporting, around 500 properties in Sussex and Kent have either no water, or have been experiencing supply issues today.

These are some of the latest pictures from Ashford, where a bottled water station has opened at Challock Village Hall for affected customers. South East Water has apologised for the disruption, citing an "increased demand" across its network.

Simon King
Lead weather presenter, BBC Weather

In the last few moments we’ve had the 13:00 BST temperatures reported and the maximum so far is now 33.5C at Heathrow.

Not only does this make it the hottest day in May on record, but also the hottest bank holiday Monday on record (exceeding the 33.3C seen in the August bank holiday in 2019).

Along with the warmest May night on record we saw last night, that’s three new major records we’ve seen today.

Temperatures will continue to rise over the next couple of hours and even away from the south-east of England, it’s hot out there with temperatures widely into the mid-to high 20s.

Temperatures continue to rise - the Met Office says temperatures of 33.5C have been recorded at Heathrow.

That provisionally further extends the record for the UK's hottest May day, which was broken just under half an hour ago.

As we just reported, temperatures in Heathrow have reached 32.9C, surpassing the all-time record for May.

According to the Met Office, the previous May record stood at 32.8C.

That temperature was recorded in Camden Square on 22 May 1922 and then again in Horsham, Tunbridge Wells and Regent's Park on 29 May 1944.

Now, 82 years later, the record for May has been surpassed at Heathrow.

Simon King
Lead weather presenter, BBC Weather

The temperature has reached 32.9C at Heathrow in the last 30 minutes.

A new May temperature record.

Simon King
Lead weather presenter, BBC Weather

Image source, Getty Images

There has been a lot of coverage recently about El Niño - the natural warming pattern in the tropical Pacific - that’s forecast to be one of the strongest on record this year.

El Niño occurs when the sea surface temperatures rise in the tropical Pacific to more than 0.5C above normal and as well as bring chaos to weather patterns around the world, leads to a higher global average temperature.

Some have asked whether the heatwave across the UK and Europe has any link to the developing El Niño.

And the answer is, no.

While the topical Pacific is warming unusually fast right now, El Niño isn’t likely to be declared for another month and its impacts will be felt later in the summer and through into 2027.

You can read more about it here.

Simon King
Lead weather presenter, BBC Weather

We’ve not even reached the hottest part of the day and the May maximum temperature record of 32.8C from 1944 has been equalled.

We will continue to see the temperature rise over the next few hours - as we’ve been reporting, 34C or possibly even 35C is possible.

But even away from south-east England, temperatures have soared into the high 20s.

Just a reminder that the average temperature for the end of May is between 14 and 20C. With temperatures today up to 15C above that average, this is an unprecedented early season heatwave.

Temperatures have provisionally matched the all-time record for May, according to the Met Office.

It says temperatures at Teddington Bushy Park, in south-west London, hit 32.8C.

The last time a place hit 32.8°C in May was in 1944 at Regent's Park, Horsham, and Tunbridge Wells.

When temperatures reach the levels they're currently at, it can be easy to overheat - which can sometimes lead to heat exhaustion or heatstroke.

Heat exhaustion usually does not require emergency medical help, as long as you can cool down, says the NHS.

But heatstroke is a medical emergency and needs immediate treatment.

Older adults, young children and people with long-term health conditions are especially at risk.

Here are the symptoms to watch out for:

Simon King
Lead weather presenter, BBC Weather

As we’ve been reporting, for an official heatwave to be declared, a location needs to reach a specific temperature threshold for three days in a row.

That threshold depends on the location.

I can confirm that with temperatures already in the high 20s and exceeding those thresholds across East Anglia and south-east England, more locations have officially gone into a heatwave.

Many other areas across England and Wales will now be on day two of meeting the threshold. With the heat continuing on Tuesday, many more of us will meet the criteria for an official heatwave.

Patrick Barlow
BBC South East

An annual bank holiday donkey derby in Surrey will not include its planned donkey racing over fears about the soaring temperatures.

Leatherhead Lions Club says both the donkey racing and a dog show have been axed "for the welfare and comfort of the animals", while attractions like fairground rides and music will still go ahead.

The decision comes as forecasters expect the May temperature record - currently 32.8C - to be broken within the next few hours.

Temperatures could rise as high as 34C in parts of the UK, according to forecasters, with Leatherhead expected to see a peak of 33C.

Simon King
Lead weather presenter, BBC Weather

Temperatures have increased rapidly over the last few hours, and in many areas it's five degrees warmer than this time yesterday.

At 11:00 BST, the highest temperature was 30.5C recorded at London's Heathrow.

This suggests that the May record - currently 32.8C - will easily be broken over the next few hours.

It’s looking inevitable that the record for the hottest bank holiday Monday - of any month - will also be broken today. It currently sits at 33.3C, set in August 2019.

Here’s how hot it is where you are at 11:00:

Cecilia Daly
BBC NI weather presenter

Image source, BBC Weather Watcher/County Down Cycling

Yesterday was the hottest day of the year so far in Northern Ireland, but today looks to be hotter again.

Temperatures are set to hit 25C in Armagh for Bank Holiday Monday although it won't be a May record breaker.

That was recorded in Lisburn in County Antrim on 31 May 1922 when the mercury hit 28.3C.

In the Republic of Ireland the highest temperature recorded on Sunday was 25.1C at Phoenix Park in Dublin.

Despite some cloudy forecasts, the UV is still high so don't forget suncream if you're out and about.

The fine, warm weather will continue through the rest of the working week, though temperatures will drop slightly.

Simon King
Lead weather presenter, BBC Weather

If you’re planning a trip to the beach, park, garden BBQ or generally spending any time outside today, make sure you’ve got sun protection.

UV levels will be unusually high across most of the UK but for parts of north-west England, the Midlands and south-east England, they will be "very high".

Very high UV corresponds to an index of 8-9 on a scale from 0 to 11+.

During summer in the UK, the UV index would typically be around 5-6 with a maximum of 8 only in exceptional circumstances.

Humans aren't the only ones finding ways to keep cool in the heat. The dogs of BBC Weather Watchers clearly know a thing or two, with one pooch donning a straw hat and shades as it lounges beneath an umbrella.

Another is spotted have a wade in the water to lower the temperature.

To keep dogs safe in a heatwave, the RSPCA recommends providing constant access to water and only taking them out in the early morning or late evening, when it's nice and cool.

Image source, BBC Weather Watchers | Bettys Hot Spot

Image source, BBC Weather Watchers | Kentavarus Way

Image source, BBC Weather Watchers | Beefy

Image source, Supplied

BBC Radio 5 Live has been taking calls from the public this morning about working during high temperatures.

Jason in Braintree is a glassblower. He says the factory "is not particularly pleasant". He says the factory can get up to between 45 and 50C when he does big jobs.

They have a fan on, and it's just "part of the job", he says, adding, "I don't think air-con would cope" with the high temperatures.

Hazel in Lampeter, Ceredigion, is a training officer for chefs. She says she is "dreading the weather getting any hotter" but that "you learn how to cope".

Image source, Supplied

Hazel's technique is to visit the larder or pastry section, which are both cooler. "It's true what they say, if you don't like the heat of the kitchen, get out," she says.

Hazel says kitchen owners should be required to ensure their staff are safe going forward, including by introducing measures like fans or air conditioning. She argues there needs to be a legal temperature where if it reaches that, chefs don't have to cook.

For context: There’s no law for minimum or maximum working temperatures in the UK, for example when it’s too cold or too hot to work. Employers do however have to stick to laws relating to health-and-safety at work, including keeping the temperature at a comfortable level.

It’s not just the UK experiencing an historic heatwave. Many May heat records have been broken across Europe over the last few days.

In Spain, 38C was recorded on Sunday. Across France and Germany, with temperatures climbing into the mid-30s, hundreds of localities saw records for May being broken.

Temperatures across the UK, France, Germany, Switzerland, Spain and northern Italy have been 10 to 15C above average for late May - and with the unprecedented heatwave expected to last for most of the week, it’s likely more local records will be broken.

Here’s how Monday’s maximum temperatures look across Europe.

Tomasz Schafernaker
BBC meteorologist

Image source, Getty Images

The heatwave that began early last week across south-western Europe is consistent with what we would expect in a changing, hotter climate.

Even by mid-summer standards, the current hot spell would be significant - let alone for May.

According to the latest European State of the Climate report, Europe is the fastest warming continent in the world with heatwaves becoming more frequent and more intense.

Since record-keeping began in the UK, there have only been a handful of years when temperatures reached or exceeded 30C in May.

Values in the mid-30s were once uncommon in the British Isles even at the height of summer, yet we are now on course to reach those levels before June has even begun.

Statistically, the UK experiences its highest temperatures at the end of July or the beginning of August, so it's likely we'll see even higher temperatures during the summer.

How hot the weather has to be for the Met Office to declare a heatwave depends on what the "normal" climate in the area is.

This varies across the UK.

The Met Office sets the temperature for a heatwave at 25C in Scotland, Northern Ireland and parts of northern England.

For many other areas of England, as well as south-east Wales, it is 26C or 27C.

And, in London, most of the home counties and Cambridgeshire, it is 28C.

A heatwave is declared if these temperatures are exceeded for at least three days. On Sunday, eight areas of England met heatwave conditions, the Met Office said.