India, May 29 -- India and Pakistan are no strangers to heat. This time of year is the worst, as heat peaks before the monsoon brings cooler conditions from June.

But this year's heat is something else. Intense, sustained heat began in mid-April. Daily maximum temperatures have topped 46degC in many locations, with some areas running around 5-8degC above seasonal norms.

The unrelenting heat has driven record demand for electricity in India as people turn on air conditioners - and worsened drought conditions affecting more than a million square kilometres across both countries.

When extreme heat combines with humidity, it can be lethal. Human bodies cannot cool themselves easily in these conditions. The heatwave has claimed at least 37 ...