The death certificate never says "death by cause of heat": Instead, doctors refer to a "heart attack" or "shortness of breath". So we had to search through huge amounts of data to find significant associations. When it became clear how many people had died as a result of the 2003 heat wave, enormous pressure was put on politicians to act.
Countries like Germany and Belgium have developed very good heat plans. When temperatures rise above 35 degrees Celsius, for instance, our university distributes free water and allows students to go home: little things. The problem is the implementation.