As temperatures look set to soar to possible record levels, spotting the signs that someone is overheating could prove to be a matter of life or death.
Heatstroke, a life-threatening condition that occurs when your core body temperature reaches 40C or higher, will be a concern to millions - especially on Monday and Tuesday.
After spending many hours in the sun, or not keeping properly hydrated, people can experience symptoms.
A national emergency has already been declared, with a red warning for extreme heat issued for the first time for England.
Temperatures could hit an unprecedented 40C early next week - and heatstroke is a huge concern for over-worked medics.
As temperatures climb and climb, we must all remember to say cool, keep hydrated, and know how to spot the signs that someone is overheating.
Here's all you need to know:
What is heatstroke?
Heatstroke, or sunstroke, is normally caused by heat exhaustion that is not correctly treated.
After spending many hours in the sun, or not keeping properly hydrated, people can experience symptoms of heat exhaustion.
Signs of heat exhaustion include a headache, dizziness, feeling sick, loss of appetite, excessive sweating, fast breathing, a temperature over 38C or being very thirsty.
Children may also become floppy and sleepy. If somebody shows these symptoms it is vital that steps are taken to cool the body down.
The person should move to a cool place, out of the sun. They should lie down, with their feet slightly raised, and drink plenty of water. Their skin should be cooled - you can spray water on them, fan them, and put ice packs under their arms and around the neck.
Most people who experience heat exhaustion should feel better once they have cooled down.
However, if you are still feeling unwell after 30 minutes of resting in a cool place and drinking water, you might be experiencing heatstroke. This should be treated as a medical emergency.
How to prevent heatstroke
There are many ways you can prevent heatstroke, and ensure you do not overheat during summer heatwaves.
It is important that you drink plenty of water to keep hydrated throughout the day.
To keep your body temperature down you should take cool baths or showers, wear light, loose clothing, and sprinkle water over the skin when needed.
You should avoid sitting directly in the sun for an extended amount of time during the peak hours of the day, which are normally between 11am and 3pm.
Brits should also avoid drinking alcohol and undertaking extreme exercise as this can further dehydrate the body, which can be dangerous during such high temperatures.
Symptoms o f heatstroke
If you continue to feel unwell after 30 minutes of trying to cool down, this could be a sign of heatstroke.
Other symptoms include a temperature of 40C or above and not sweating even though you are very hot.
Sufferers may also be feeling very confused, and experience shortness of breath.
More serious cases can see the person experience a seizure, lose consciousness and become unresponsive, so it is vital that they are quickly given the necessary medical treatment.
You should call 999 if you suspect someone has heatstroke.
Here is the NHS list of symptoms:
- Headache
- Dizziness and confusion
- Loss of appetite and feeling sick
- Excessive sweating and pale, clammy skin
- Cramps in the arms, legs and stomach
- Fast breathing or pulse
- A high temperature of 38C or above
- Being very thirsty
