It is the season where serious heatstroke occurs in Japan.
I feel the situation is getting more serious every year, and one of the reasons could be global warming.
The major causes of heatstroke are high temperature and humidity. Our bodies cannot control the heat of the core temperature, because sweat cannot evaporate in high-humidity conditions.
In Japan, the weather forecasts of NHK (the national broadcasting company) show and report the level of heat and danger. There are 5 levels (danger, strict caution, caution, be careful and safe) and these are expressed by faces and colors as shown in the picture below.
In Japan, many people die because of heatstroke in summer, especially the elderly and children.
The incidents which happen every year are children being left in cars where the temperature goes up over 50 degrees and elderly people die in hot rooms because they don't have air conditioner or use it in their apartments.
Japanese summers are very hot and the temperatures reach sometimes up to nearly 40 degrees. Moreover, the humidity comes with the heat makes the temperature feel much higher and more uncomfortable.
When you travel in Japan in summer, make sure you stay hydrated, otherwise you can easily get heat exhaustion or heatstroke.