Experts are warning about the health risks of heatwaves as temperatures continue to climb across the country this week.

The mercury is expected to hit the mid-30s in the south of England before Friday, leading forecasters and medics to tell people to take extra precautions to stay safe in the sun.

Warnings have been issued about UV levels, which are going to be “exceptionally high” over the next couple of days.

Met Office meteorologist Alex Burkill told the PA news agency that UV levels will be “reaching eight across many places and will be reaching nine across parts of Devon and Cornwall tomorrow.

“That’s about as high as it gets really in the UK.

Warmest UK June temperatures
(PA Graphics)

“The sun is as strong as it gets at the moment because we’re so close to the solstice.

“We’ve got peak sun strength, clear skies, plenty of sunshine – it’s the perfect ingredients for high UV.”

Mr Burkill advised anyone outside for prolonged periods of time on Wednesday and Thursday to take measures to protect themselves.

Shoppers have also been advised to be aware they could be forced to spend extra time in the sun as a result of social distancing measures.

Dr Lynn Thomas, medical director at St John Ambulance, said: “You could end up in the sun for longer than expected on what would normally be a quick journey, such as queuing to enter the supermarket, so you should be prepared to look after yourself and others.”

She added: “Heat exhaustion and heatstroke are two of the most serious problems that can develop when the mercury soars but by being prepared you can spot the early warning signs, such as headache and dizziness.”

London Fire Brigade (LFB) has warned people not to have barbecues on dry grass, not to drop cigarettes or matches, and not to leave rubbish such as glass bottles lying around amid a risk they could start fires.

LFB Deputy Commissioner Richard Mills said: “Barbecuing on dry grass is thoughtless and reckless and can easily be the cause of a significant fire, which isn’t something you want on your conscience.

The public is also being reminded to take care around water throughout the summer, amid concerns people might be tempted to take a dip to cool down.

Emergency services rushed to the River Thames in Cookham, Berkshire, on Tuesday evening amid reports that a man was missing after going into the water.

Beaches were busy as people took advantage of the good weather after the months of lockdown spent at home.

Summer weather June 23rd 2020
A busy beach in Margate, Kent. Britain is braced for a June heatwave as temperatures are set to climb into the mid-30s this week.

Tuesday was not quite the hottest day of the year, as the 28.6C recorded at Heathrow Airport and Kew Gardens fell short of the 28.9C recorded at the end of May.

“But we are going to beat it tomorrow and the day after,” Mr Burkill said.

He predicted temperatures would edge towards 33 degrees as we experience “lots of hot and sunny weather through the next couple of days”.

The forecaster added: “The heat is going to be quite widespread, even across parts of Scotland we could be looking at highs of 26 or 27.”

“The nights are going to be uncomfortably hot as well, so people who are susceptible to the heat will struggle.”