Q&A: Heatwave health risks
How dangerous is the hot weather to our health and what precautions should we be taking?
When does hot weather turn into a heatwave?
During a heatwave there are consecutive days - at least two - of high, but most importantly no real dip in the heat at night leaving little opportunity for people to cool off.
A heatwave warning is not triggered by a specific temperature but is based on a threshold at which deaths are expected to increase due to consistently high temperatures across large areas of the country.
Level four is the highest alert, which is reached when high temperatures are expected on four or more days in two or more regions of the country.
Are heatwaves getting more common?
According to a Department of Health report, climate change means that heatwaves are likely to become more frequent in England.
The worst heatwave in recent years happened in August 2003 when record-breaking temperatures led to 2,000 excess deaths in the UK.
Northern France bore the brunt of the hot weather that year when three weeks of unprecedentedly high temperatures resulted in 15,000 excess deaths.
By the 2080s, it is predicted that an event similar to that experienced in England in 2003 will happen every year.
So why is a heatwave dangerous?
Consistently hot weather poses a risk to health because it can interfere with the body's ability to regulate its temperature.
For most healthy adults and children, as long as they drink plenty of water and avoid baking in the midday sun, it should not pose a problem - other than perhaps being uncomfortable.
But for the elderly, very young, and those with chronic medical conditions, the health risks are potentially significant.
Most of the extra illness and death seen during a heatwave is caused by respiratory and cardiovascular diseases.
It can also cause rashes, fluid retention, and dizziness and fainting.
Heatstroke is the most dangerous condition, where the body can no longer control its temperature, and people become confused, disorientated, have fits, and fall unconscious.
Left untreated, it can lead to organ failure and brain damage.
What can people do to limit the risks?
The advice is to be prepared, especially those people who are most vulnerable, and to check on neighbours and relatives who may be at risk.
Stock up on food and drink and make sure that those who take regular medicines have adequate supplies.
Drink plenty of water and keep in the shade where possible - particularly taking care to avoid the sun in the hottest part of the day between 11am and 3pm.
Stay in the coolest room in the house, close blinds and curtains if necessary and also keep windows shut when it is warmer outside than in, opening them at night when it is a bit cooler.
Ultimately if you or anyone else feels unwell, the best thing to do is to drink water and go somewhere cool to rest.
Anyone experiencing breathlessness, chest pain, confusion, dizziness, weakness or cramps that get worse or persist, should seek medical help.
How do care homes and hospitals prepare?
All care homes and hospitals will have a heatwave plan in place.
With a level two warning, they should be monitoring indoor temperatures.
They should also make sure there are cool areas that patients or residents can retreat to if necessary and supply lots of cold water and ice.
Most importantly, they should identify those in their care who are most at risk to keep an extra close eye on them.
This might be those who are taking medicines which interfere with the body's ability to regulate its temperature, or those with conditions, such as heart disease, that increase their chance of problems.