What are heatwaves?

The 2003 UK h heatwave left its mark on people's minds. Increasingly frequent in the UK and throughout the world, these periods of extreme heat are characterised by very high temperatures during the day, but also at night. So what are the heatwave thresholds in France and the health risks? How to cope with it? Drink a lot of water, but still?

Heatwave, when high temperatures are harmful to health

The heatwave that hit the UK in 2003, has made this phenomenon very popular by placing it at the centre of people's worries. When the temperature rises so high that it doesn't drop at night, and every evening the weather forecast says that the heatwave will continue, it is important to be careful in order to avoid putting your health at risk.

What are the health risks of heatwaves?

A heatwave is not declared when the temperature reaches a certain level. It all depends on the country and its climate: the heat in the UK is not the same as in Mali. It's all relative, but while it's difficult to compare the temperatures that define a heatwave, one thing is certain: a heatwave means alert, vigilance, and caution.
Indeed, like periods of extreme cold, heatwaves are times when the temperature puts the human body (and all living beings) to a severe test. This heat is even more dangerous for people at risk, such as babies, children, pregnant women, the elderly, and the sick.

Why do heatwaves have these adverse effects on health? Simply because the intense and continuous heat makes you feel tired and dehydrated (when the water level in the body becomes insufficient). In addition, it can lead to heatstroke, illness, or aggravation of existing conditions.
In the UK, the 2003 heatwave heatwave caused many deaths (about 15,000). Since then, the country has put in place the 'heatwave plan' to reduce the health effects of heatwaves: thanks to this, the heatwaves that followed caused a very limited number of deaths.

Heatwave in the UK

As mentioned above, heatwaves vary according to the country and its climatic conditions.
The UK is in Western Europe and for this geographical area, a heatwave is generally defined as a heatwave where the night-time temperature is above 18-20°C while the daytime temperature rises above 30-35°C.
When the weather forecast announces such temperatures, it also warns that it is important to drink plenty of water, not to go out, and to stay cool to preserve your health.
On the other hand, in big cities such as London, Manchester, or Leeds, the temperature is even higher because the walls retain heat, air-conditioning units emit heat into the street and cars cause a high level of air pollution which reinforces the heat.

The heatwave is not felt in the same way in all regions in the UK: it depends on the weather, each territory being more or less affected by the heatwave. The most affected areas have been placed on heatwave alert to encourage residents to be vigilant.

Knowing the exact temperature at the right time can help you protect yourself from heat waves. With the Netatmo Smart Weather Station, stay informed in real time to air out as soon as the temperature drops and the air is cooler. The more information you have about the weather during this period, the better you'll be able to manage it.

Heatwave thresholds reassessed each year in the UK

Please note that just because the temperatures are high and the heat persists does not mean that the UK is automatically declared to be in a heatwave situation. According to scientists, this requires temperatures to exceed certain thresholds during the day and night for at least 3 days and 3 nights in a row.

These thresholds are updated every year, as is the "heatwave plan" mentioned above. In the UK, the heatwave thresholds are based on daytime temperatures and vary from one region to another. In 2003, for example, in the British Isles, it was 31 degrees and in Ballywatticock in Northern Ireland 36 degrees. At night, the temperature thresholds vary from 18 to 21 degrees depending on the region.

Velux Active with Netatmo technology uses smart sensors to monitor temperature, humidity and CO2 levels inside your home. The goal? To automatically control the opening of your roof windows to ensure an optimal temperature and thus avoid heat waves, which are dangerous for your health.

What are the differences between heatwaves and extreme heat?

Although hot weather and heatwave phenomena seem similar, scientists insist that there are real differences between the two.
The difference between hot weather and a heatwave is that the above-mentioned thresholds are exceeded. As long as they are not exceeded, the heatwave alert and the associated plan are not triggered.

However, one thing remains the same: heatwaves and hot weather have been increasing for decades in France and throughout the world. In addition to the general temperature increase of 2 to 10 degrees by 2100, hot weather and heatwaves will also be much more frequent and almost annual. Studies continue to prove this day after day and link this trend to climate change caused by humans.