Paris saw a record high temperature of 42.6C (108.7F) on Thursday, amid a heatwave that broke records across Western Europe, reports BBC News.
A red alert was issued in north France. Germany also set a new national temperature record of 41.5C - bypassing the figure set just a day before.
The UK recorded a record temperature for July of 38.1C, with trains told to run more slowly to stop rail buckling.
The Netherlands also recorded its highest ever temperature at 40.7C.
"Climate change has increased the likelihood and severity of heatwave episodes across Europe," the UK's national weather service said.
French authorities launched a red alert - the highest state of alert - in the Paris region and 19 other districts and said temperatures were expected to reach 42C-43C in parts of the country.
French media said Wednesday night was "probably" the hottest ever recorded in France.
Belgium's Royal Meteorological Institute issued "code red" warnings across most of the country - urging people to take extra precautions during "extremely high temperatures".
In France, officials warned people to avoid travelling to work from home if possible. Some nurseries have been closed.
The chief architect responsible for restoring Notre-Dame warned that the extreme heat could lead to the cathedral's roof collapsing if the joints and masonry holding up the roof dried out.
French reports suggested five deaths may have resulted from the high temperatures.
Comparisons were drawn to a heatwave in August 2003 which contributed to almost 15,000 deaths in the country.