These heat waves, occurring over the last several decades, have caused the greatest number of deaths, according to world meterorological organizations.
Deadliest Heat Waves
![An Indian auto rickshaw driver rests on a hot summer day in Hyderabad, India, May 25, 2015. So far, more than 1,826 deaths have been attributed to the heat wave.](https://gdb.voanews.com/3f841a20-f861-4521-ac4d-f6f944de77d8_w1024_q10_s.jpg)
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An Indian auto rickshaw driver rests on a hot summer day in Hyderabad, India, May 25, 2015. So far, more than 1,826 deaths have been attributed to the heat wave.