Danger Days Heat Up American Cities

Thousands of Los Angeles homes and businesses lost power this weekend after blistering heat caused temperatures to climb into the triple digits, taxing an already strained electrical grid as residents cranked up their AC.

In addition to power outages, heat waves are the single biggest cause for weather related deaths, taking more lives on average than hurricanes, floods, and tornados. Meteorologists define the heat index, or danger days, as heat and humidity combining to create real feel temperatures above 105 °F or 40°C.

U.S. cities are expected to experience more danger days in the coming years as extreme weather becomes the norm due to increased levels of carbon dioxide.