Babies and elderly most at risk when temperatures soar
Babies, young children and older people, especially those over 75, are among the most at risk in heatwave temperatures.
Soaring temperatures can lead to illness and in extreme cases death.
The main short-term dangers are dehydration from not getting enough water to drink, heat exhaustion and heatstroke.
Dehydration occurs when the body's water content is reduced.
It can prevent the body's systems from regulating themselves and can cause a number of complications.
Heat exhaustion occurs when the body's temperature rises to between 37C and 40C, causing nausea, faintness and heavy sweating.
Heatstroke sets in if the body's temperature prevents the cells and body systems from functioning normally.
Those affected may develop rapid breathing, headaches, lethargy, confusion and even loss of consciousness.
Unless emergency treatment is given, it can result in multiple organ failure and death.
Whatever the outside temperature reads, motorists need to add many more degrees for inside the car.
Parents are advised to never leave infants or young children unattended in a vehicle, even if the windows are partially open or the air conditioning is on.
If families are travelling to a hot country, they should be particularly careful for at least the first few days, until they get used to the temperature.
The advice for all age groups who are vulnerable to extreme temperatures is to keep out of the sun between 11am and 3pm.
If you have to go out in the heat, walk in the shade, apply sunscreen and wear a hat and light scarf. Avoid extreme physical exertion.
The signs of heat exhaustion include headache, dizziness and confusion, feeling sick, excessive sweating and pale clammy skin, cramps in the arms, legs and stomach, fast breathing and intense thirst.
When dehydrated the body also loses salt and sugar. A child should be given a mix of water, juice and soup to get back the sugars, salts or minerals they have lost. If a child is very overheated, move them to a cool place.
Remove any unnecessary clothing. Get them to lie down and raise their feet slightly. Cool their skin - spray or sponge them with cool water and fan them.