On August 12, 2021, most of the United States registered a daily high temperature above 90°F. Our Hourly Electric Grid Monitor shows that hourly electricity demand in the Lower 48 states reached 720 gigawatthours (GWh) for the hour ending 5:00 p.m. eastern daylight time (EDT) on that day, which is the highest reported value for a single hour since balancing authorities (BAs) began reporting hourly electricity demand to us in July 2015. The previous hourly high was 718 GWh reported for the hour ending 6:00 p.m. EDT on July 20, 2017.