Hazel Shearing
Education correspondent

There's no set temperature at which schools are told they need to close in a heatwave - that decision is made on a case-by-case basis.

I asked Tim Warneford, whose consultancy helps schools obtain funding for their buildings, whether he expected quite so many to do so.

"I think it was a ticking time bomb," he replies, since England's ageing school estate was "not built to withstand the temperatures that we are now facing and are likely to face into the future".

"New buildings, we hope, will be designed sufficiently well that will reduce that risk, but the overwhelming number of our stock is going to require retrofit - and therefore that's going to require a certain amount of money," he adds.

A big problem is that many schools built in the 1950s and 1960s have "almost floor-to-ceiling windows" which trap in heat and are challenging to ventilate.

He adds that only schools built in the past decade or so are likely to have been designed with air conditioning units - and warns that some of those may not even be up and running because they're expensive to maintain.

Chris Fawkes
BBC Weather

Last night was the warmest on record for some UK sites, including at Brize Norton (Oxfordshire) where temperatures only fell to 22.3C - what is known as a tropical night.

From this warm and humid start, temperatures are rocketing upwards. Even before midday we've reached 31.6C at Thorney Island (Hants).

The June record of 35.6C is going to get smashed later this afternoon, with highs of 37 or 38C likely around 15:00 BST in southern England.

This would put us well inside the top ten hottest days ever recorded in the UK.

Global heating is to blame for such unprecedented heatwaves. You may remember that last month the May record was pulverised by well over 2C - it's clear that our climate has changed.

Matt McGrath
Environment correspondent

Image source, Justin Tallis/AFP/Getty Images

A meeting in London on how to adapt to extreme heat has fallen victim to the very thing it was seeking to tackle.

The session, scheduled at the London School of Economics during London Climate Action Week, was due to explore how countries and cities are responding to rising temperatures around the world.

But organisers cancelled the event after the Met Office issued a red extreme heat warning.

Chris Anderson from Practical Action, who was due to take part in the event, says: “We're fully in favour of the decision, for the wellbeing of attendees and panellists.

“But it shows that extreme weather is becoming unpredictable and moving faster than people can adapt, even in the richest countries.”

Beth Rose
Disability affairs reporter

Image source, Getty Images

As temperatures rise, the effectiveness of medications can change.

The Medicines and Healthcare products Regulatory Agency (MHRA) says heat damage can break down active ingredients in medicine.

That can stop or alter how much the body absorbs when it comes to tablets, inhalers, hormone patches, insulin, blood glucose monitors and EpiPens.

Dr Alison Cave, MHRA’s chief safety officer, says some medicines can also make you more likely to "burn in the sun, feel dizzy, or get dehydrated", especially if you’re taking diuretics or have a condition like asthma, heart disease or diabetes.

She says most medicines need to be stored at temperatures below 25C - but cars, trains and even bags and pockets could get warm enough to cause problems and keeping them in a cool bag could be useful.

She adds: "If your medicine has changed colour, developed an unusual smell, changed texture, or looks different in any way, this could signal heat damage. Ask your pharmacist for advice."

Does the warm weather have an impact on the economy?published at 11:53 BST 24 June

11:53 BST 24 June

Dharshini David
Deputy economics editor

As some trains grind to a halt - is the economy in danger of doing the same?

The answer is no - after all, whatever the disruption, most of us are still working.

And while events are being cancelled, that activity may simply be displaced if they are rescheduled. Equally, other forms of spending - on fans, ice cream and extra childcare if you’re dealing with school closures - may rise.

So, however tempting, it’s impossible to put a reliable number on this.

In the grand scheme of things, short-lived weather events don’t tend to shift the dial much in terms of overall GDP. But economic activity may be a bit sluggish overall for a few days as the temperature rises.

Miho Tanaka
Senior climate journalist

Image source, Gwyndaf Hughes/BBC

The Engine Room in Tottenham Hale normally serves as a community centre for local residents to get together for walks, and arts and crafts.

But this week it is serving another purpose - a “cool space”.

One of dozens designated across the capital offering respite from heat for residents, mostly elderly people.

The spaces have air conditioning systems, seating, free drinking water and bathrooms.

Frederica Roberts, tells the BBC the centre offers them ‘”absolute tranquillity” away from the “hustle and bustle”.

Her friend, Marion Wilson, jokes that spending time at the centre offers them “a relief especially with half of us that are menopausal. If you have that and you have heat, it's not good to be around us”.

Rory Bibb
Reporting from London

Johnny is a construction worker on a site in London where temperatures are already soaring.

He says: "It’s horrible. You’re outside all day and there’s no let up. We might be going home early, but there’s work to be done."

"We're all hot, and we're all in the same boat. No one's dropped down, touch wood,” he adds.

UK employers are issued health and safety advice on how to protect outdoor workers in these sorts of conditions.

But there is no legal maximum temperature at which work has to stop as there is elsewhere, meaning it's business as usual for people in industries like construction and farming.

Another amber weather warning has just been issued by the Met Office.

It will come into effect between 00:00 and 21:00 on Saturday, covering parts of southern and eastern England.

Image source, Met Office

Image source, Getty Images

Europe's ongoing heatwave is expected to continue on Wednesday.

France is experiencing another day of exceptionally hot weather, with more than half the country remaining under a red heat alert on Wednesday.

It comes after the country experienced its hottest June day since records began on Tuesday, with an average temperature of 29.8C (85.54F) recorded.

Temperatures are expected to peak in the Netherlands and Belgium on Friday, while Germany is expected to see the mercury rise to 40C (104F) over the weekend.

Image source, BBC Weather

Ben Rich
Lead weather presenter

The Met Office has been issuing extreme heat warnings since 2021 – and this is only the second time that a red warning that has been issued since then.

The first was in July 2022, when the UK set its new all-time temperature record of 40.3C.

When the Met Office issues weather warnings it takes two things into account: how likely it is that severe weather will happen, and what impact that weather is likely to have.

A red warning is issued when there is a high likelihood that severe weather will have a high impact, and that is definitely the case with this heatwave.

There is a risk of health impacts across the population and a threat of significant disruption to power networks and transport services.

Image source, EPA/Shutterstock

The National Rail website is warning passengers not to travel to, from, or within the red weather warning zone unless absolutely necessary.

The Met Office has previously warned that rail journeys are among the daily activities that could be impacted by the extreme heat.

A number of rail operators have altered their services, in response to the heat, alongside warnings that there could also be short-notice changes or alterations.

The operators listed on the National Rail website as having disruptions, ticket changes or travel advice are:

• Avanti West Coast
• c2c
• Chiltern Railways
• CrossCountry
• East Midlands Railway
• Elizabeth line
• Gatwick Express
• Great Northern
• Greater Anglia
• Great Western Railway
• Heathrow Express
• London Northwestern Railway
• London Overground
• LNER
• Merseyrail
• Northern
• Southeastern
• Southern
• South Western Railway
• Stansted Express
• Thameslink
• TransPennine Express
• Transport for Wales
• West Midlands Railway

Grand Central, Hull Trains, Lumo and ScotRail are all operating on a normal timetable with no planned alternations, but passengers have been advised to check before they travel in case of short notice alterations.

Sadaf Maruf
Your Voice news editor

Image source, Supplied

Helen and her husband Tony live in the northeast part of Shetland, in the hamlet of Lunna.

She got in touch with BBC Your Voice on Wednesday to say that for them it was a balmy 14C.

She says there is a lot of mention on the news of how hot it is south, "but the forecast here is for a maximum of 15C".

Helen who works from home in the pharmaceutical industry says, "if it got to 20C the sheep would probably lie around panting". The couple have lived in the hamlet of Lunna for 25 years.

She says: "I’ve put on a woolly dress and a vest on today! Even though its baking hot in the south, we prefer it here by far. Just a bit of warmth every now and then would be nice though - for us 20C is tropical."

The Met Office has extended the red extreme heat warning in place by three hours until 23:59 on Thursday evening.

The warning has also been extended south across Dorset, Hampshire and Sussex, the Met Office say.

It has also issued another amber warning for heat for Friday, covering eastern and central England, alongside the existing red warning.

Image source, Met Office

Matt Taylor
BBC Weather

Jersey experienced its hottest June day on record on Tuesday.

The Jersey Met Service reported a high of 37.2C (99F) - smashing the previous record of 33.4C, which was only set last year, by a huge margin.

It was also their second warmest day on record.

Image source, BBC Weather Watchers / Hedi

It was a notably warm start this morning, although it hasn't deterred some from getting out and about.

Here are some pictures taken by BBC Weather Watchers from across the UK.

Image source, BBC Weather Watchers / Hayley85

Image source, BBC Weather Watchers / Steve

Image source, BBC Weather Watchers / Philbert Nut

Image source, BBC Weather Watchers / Kryzstof

Water safety experts have shared some simple tips with BBC News on staying safe when swimming in open water. Here’s what they told us:

Choose a spot with a lifeguard: The best place to swim is somewhere supervised. You can find a list of UK beaches with lifeguards on the RNLI website, external, external.

Watch videos of rip currents: A rip current can quickly pull you away from shore and out of your depth. They can be difficult to spot, RNLI says, but watching videos can help you identify them.

Think about your swimming ability: Swimming in the sea, lakes and rivers is very different from a swimming pool, so people should think carefully before getting in.

Keep someone on shore: Someone from your group should always stay on shore to keep an eye on those in the water and can call for help if needed.

Avoid inflatables: If the wind changes when you’re in an inflatable, you can be blown out to sea. It’s advised to avoid them altogether.

Get in the water slowly: Getting into cold water too quickly can cause cold water shock, which restricts your ability to move and affects your breathing. You should get in slowly and allow your body to acclimatise.

Image source, PA Media

More than 500 schools in Wales have been closed or partially closed as a result of the high temperatures.

Closures are impacting schools across mid and south Wales - including all in Blaenau Gwent, and most in Caerphilly and Bridgend.

Others have been confirmed in Cardiff, Carmarthenshire, Merthyr Tydfil, Monmouthshire, Neath Port Talbot, Newport, Powys, Rhondda Cynon Taf, Swansea, Torfaen and Vale of the Glamorgan.

That's on top of at least 578 full or partial closures in England - the vast majority of them in the south of the country.

Ben Rich
Lead Weather Presenter

Yesterday’s highest temperature was 34.6C at Wisley in Surrey – but today is likely to be even hotter.

Strong sunshine will lift temperatures well into the 30s Celsius with highs of 37C likely – with the hottest place likely to be somewhere to the south-west of London or in central-southern England, within the area covered by the red extreme heat warning from the Met Office.

It is likely that the UK’s June temperature record, currently 35.6C, will be broken.

Temperatures of 30-34C are expected across large swathes of south-west England, east Wales, the Midlands and Northern England.

High humidity will make it feel particularly hot when combined with the strong sunshine.

Scotland and Northern Ireland had their hottest day of the year so far yesterday, but today is likely to be cooler with temperatures peaking in the low to mid-20s.

Image source, EPA

On Thursday, we’ll be running a live Q&A with correspondents and experts from BBC teams including climate and science, health, learning and identity, business and weather.

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Hazel Shearing
Education correspondent

There's no official data to show how many schools are closing because of the heat, so we've been looking through council and school websites to try to get an idea.

So far we've counted at least 578 full or partial closures - the vast majority of them in the south of England.

The total number is likely to be much higher, though, because many councils do not publish lists of schools which have to close unexpectedly due to extreme weather.

Lots of schools are also part of multi-academy trusts, which may not appear on council lists if they're closed.

The disruption comes just after the end of timetabled GCSE, A-level and other exams.