The UK and most of Europe experienced two unprecedented heatwaves in May and June.
Tens of millions of people endured extreme temperatures over the weekend as the heatwave moved east across the continent, placing increasing pressure on health systems.
The restriction comes as France marks the annual Fête de la Musique, a nationwide street music festival that draws millions of people outdoors each summer.
France banned alcohol in red-alert areas on Sunday, Spain and Germany cancelled sports events, and Britain warned of "tropical nights" as Europe sweltered through a heatwave.
The UK's Royal Life Saving Society on Wednesday issued warnings on water safety after nine people died in the sea, rivers and lakes during days of record-breaking hot weather.