Japan's summer weather is as predictable as a straight-to-DVD action flick. First comes the rain, then weeks of stifling temperatures accompanied by a rash of heatstroke incidents. But this July has taken on a hyperbolic tone. After opening with an unprecedented amount of rainfall the tireless assault of scorching temperatures have sent a record number of people to the hospital for heatstroke.

Over 21,000 people were hospitalized for heatstroke last month, according to the Fire and Disaster Management Agency. That's the highest...