Heatwave warnings have been issued as the temperature is expected to soar above 30°C in south London tomorrow.

The Met Office has warned there is an "80 per cent probability of heatwave conditions" in parts of England between noon today and 6am on Thursday.

Its warning predicts the "hottest day of the year so far" this week with the temperature forecast to peak tomorrow.

The alert said: "Heatwaves can be dangerous, especially for the very young or very old or those with chronic disease."

NHS organisations have called on people to look after themselves and others as the heatwave hits.

Clinical chair of Surrey Downs CCG Dr Claire Fuller said: "It is great to see the sun shining again, but we know that the hot weather can cause serious problems, especially for people with existing heart, lung or kidney conditions.

"Each year doctors see lots of patients suffering from sunstroke and dehydration, so it's really important we all do all we can to keep ourselves, and others, safe.

<blockquote class="twitter-tweet" data-partner="tweetdeck"><p lang="en" dir="ltr">I cannot emphasise how hot it is <a href="https://twitter.com/Wimbledon">@wimbledon</a> - sun tan lotion & water essential. Sweltering on court 3 <a href="http://t.co/7tlgz84087">pic.twitter.com/7tlgz84087</a></p>— ylgsport (@ylgsport) <a href="https://twitter.com/ylgsport/status/615854626336866304">June 30, 2015</a></blockquote>
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"By taking a few simple steps, like staying out of the sun at peak times, keeping well hydrated, using sunscreen and looking out for older relatives and neighbours, we can make the most of the good weather and stay sun safe at the same time."

Surrey Comet:

This Met Office forecast for Sutton shows the heatwave will hit hardest between 4pm and 6pm

South East Coast Ambulance Service is preparing for a spike in calls relating to sunburn, dehydration and heat stroke.

Andy Cashman, head of contingency, planning and resilience, said: "Most people will be grateful of the fine weather and are going to be keen to get out and enjoy the summer weather.

"However, we’d simply ask that they are sensible and cover up and use sun cream, drink plenty of water and use their common sense.

"The very young, older people and those with pre-existing conditions need to be particularly careful but the sun can be harmful for everyone."

Heatwave advice (from Surrey Downs CCG)

• Wear UV sunglasses, preferably wraparound, to reduce UV exposure to the eyes, walk in the shade, and apply sunscreen of at least SPF15 with UVA protection

• Make sure to wear a hat, a light scarf, and light, loose-fitting cotton clothes in order to minimise the risk of sunburn

• Drink lots of cool drinks, avoiding alcohol. Remember to carry a bottle of water with you if travelling

• Try to keep out of the sun between 11am to 3pm, and seek shade during those times

• Look out for others, especially vulnerable groups such as the older people, young children and babies, and those with serious illnesses

• Never leave anyone in a closed, parked vehicle, especially infants, young children or animals Further advice can be obtained from NHS Choices at www.nhs.uk/summerhealth, NHS 111 or from your local chemist.