Humidex — one way of getting a truer measurement of the summer heat's effect on the body
Parts of Europe suffer a heatwave but you got to weigh in humidity to get closer to the real impact. Meteociel displays the Humidex readings all over Europe, taking humidity into account. Check chart below for guidance
Forecast for France and some surroundings https://www.meteociel.fr/modeles/gfs/humidex/3h.htm
Humidex measurements http://www.meteociel.fr/observations-meteo/humidex.php?region=eur2
There may well be better scales for assessing this, but Humidex has the distinct advantage of actually being reported for European weather.