Forecasters have expected that temperatures could hit 27C on Thursday in London. Last week, London experienced temperatures as high as 34C.
In such unusually hot weather, people have been asked to keep a close check on the elderly, the vulnerable, and those most at risk of heat exhaustion.
Here’s what you need to know about the effects on your body.
What does extreme heat do to our bodies?
Extreme heat has a negative impact on the human body, because as the body gets hotter, the blood vessels open up, leading to lower blood pressure, and making the heart have to work harder.
This can cause mild symptoms such as itchy heat rash, or swollen feet, as the blood vessels become leaky.
Meanwhile, excessive sweating can cause an accelerated loss of fluids and salt, causing the balance between them to shift.
These two combined can lead to heat exhaustion, the symptoms of which include dizziness, nausea, fainting, confusion, muscle cramps, sweating, and tiredness.
Bodies attempt to keep their core temperatures at below 37.5C, which is how they have evolved to maintain body temperatures in hot or cold environments.
What should I do if I see someone suffering from apparent heat exhaustion?
If someone has returned to a normal temperature within an hour, then, they are usually not suffering from dangerous heat exhaustion.
However, if they don’t appear to have recovered within 30 minutes, then they could start to suffer from heatstroke, which is a medical emergency, and should result in a call to 999.
How can I stay safe in the heatwave?
In order to stay safe during the heatwave, there are a number of things you can do.
The UK Health Security Agency has a number of tips available on their website.
Look out for those who may struggle to keep cool, such as older people, those with underlying conditions and and those who live alone
Stay cool indoors by closing curtains on rooms that face the sun
Drink plenty of fluids and don’t drink too much alcohol
Don’t leave anyone, especially babies, young children and animals, in a locked vehicle
Keep out of the sun between 11am and 3pm when the sun’s rays are strongest
Keep in the shade, use sunscreen with a high SPF and UVA rating, and wear a wide-brimmed hat
Avoid physical exercise in the hottest part of the day
Take water with you if travelling
Be aware of hidden dangers in rivers and open water if tempted to cool off
The Red Cross also has tips on how to stay safe, which include:
Take actions to keep your house cool during the heatwave, including covering windows with drapes or shades
Planning to go to a cool place, such as checking if malls or public libraries are open
Contact a nearby neighbour, friend or relative who has air conditioning.