Started on July 14, 2011, Japan Meteorological Agency started Extreme High Temperature Forecast to raise the awareness of heat stroke.
This forecast will issue "high tempreture warning" for each prefecture except Hokkaido and Okinawa when the high tempreture forecast of the area are expected to exceed 35 degree Celcius (95 F).
JMA decided to launch this special forecast because many Japanese, especially the elderly, tried to stop using air conditioner in order to save the electricity, and ended up having heat stroke. As people becomes older, some will no longer feel the heat or control the body tempreture.
By issuing heat warning, JMA hope to recommend people to use adequate measurement. People need to use air conditioner.
Also this is very good for the travelers that you should be careful. Even the traveler are from high tempreture climate region, Japan's summer heat is very humid. The humid 35 C (95 F) tempreture feels much hotter and uncomfortable than the dry 35 C.
JMA issues Extreme High Temperature Forecast at 5 am and 11 am. You should check the Internet before you leave.
Also, make sure to read JTG: Heat Alert in Japan