The Environment Ministry will put in place on Wednesday a special alert system for heatstroke to protect people from unprecedented heat.
Under the new system, which will remain until Oct. 23 for this year, an alert will be issued for prefectures when unprecedented, dangerous heat could cause serious damage to human health. People will be urged to use air conditioning and avoid outings.
A special alert will be issued at around 2 p.m. when the heat index, based on factors such as temperature and humidity, is forecast to hit 35 or higher at all monitoring points in a prefecture the following day.
The new system will supplement an existing one under which a heatstroke alert is issued when the index is forecast to reach 33 or higher at any of the monitoring points in a prefecture.
The heat index, available at some 840 points across Japan, has never surpassed 35.
When a special heatstroke alert is issued, people will be asked to avoid nonessential outings, stay in air-conditioned rooms and stay hydrated, among other steps.
For the aged, babies and infants, who are vulnerable to heatstroke, the ministry will ask families and local communities to help them stay in cool rooms.
Municipalities designate public and private facilities equipped with air conditioners as cooling shelters. Such facilities will be required to be open for the public as temporary shelters when a special heatstroke alert is issued.