The number of people who develop heat disorders increases in August on days when the air temperature is highest. In addition, when the temperature remains high night after night, a person's body temperature remains high even at night, and this can result in heat disorders.
Emergency hospitalizations due to heatstroke start to occur on midsummer days (when the high is above 30 degrees) and increases rapidly on very hot days (above 35 degrees). (Morimoto, 2015)