Elderly people often don’t have the feelings of thirst.
France is making preparations to avoid a repeat of summer 2003, when supermarket store rooms had to be used as emergency morgues to deal with the huge number of heat-related deaths.
Around 15,000 people died as a result of the weather that summer, many of whom were vulnerable elderly people.
The county was unprepared for the weather and in response to mortuaries rapidly filling up, replacements were set up in refrigeration lorries.
The high number of deaths resulted in mass funerals in Paris, with 57 people being buried on the same day at one cemetery.
As a result of summer 2003, an alert system was introduced in France which aims to warn people about expected highs and avoid more deaths.
There were also heat-related deaths in the UK (2,000), Portugal (2,100), Italy (3,100), Holland (1,500) and Germany (300) that year.