What would you guess is the deadliest disaster in Minnesota history? A wildfire? Blizzard? Tornado? It was none of those. In 1936, a long-term heat wave killed at least 900 across Minnesota.

Heat is America’s top weather killer, even in the age of air conditioning and community pools.

For the return of the long-running Climate Cast, we wanted to revisit the terrible cost of the 1936 heat wave that hit 90 years ago this month. On July 14, 1936, experts estimated a person was dying every three minutes in Minneapolis alone as a direct result of the heat.

In this episode, MPR News chief meteorologist Ben Cathey speaks with with Geoff Williams, the author of a new book, “The Summer of Death.” Williams calculates that at least 12,000 people died across America. He thinks Minnesota’s official death toll is likely severely under-calculated.

Click play on the audio player above to listen to this episode or subscribe to the Climate Cast podcast.