All seven U.S. regional independent electric grid operators set new record demands in July as they met the challenge of record high temperatures without incident. Peak demands reached in areas with independent system operators (ISOs) and regional transmission organizations (RTOs) ranged from 0.9% to 4.5% higher than the peak levels reached in 2005. Regional grid operators reported a new aggregated peak record of electricity usage of 483,233 MW during one week of extreme heat and high humidity in the United States. Last year the peaks for the grid operators was 475,717 MW. ISOs and RTOs serve two-thirds of the U.S. population.

High temperatures, lightning and high winds have caused more than 765,000 Southern California Edison (SCE) customers to lose power — ranging from flickering lights to lengthy outages. As of July 25, SCE had identified more than 725 transformer failures resulting from weather conditions.

A half million Ameren customers across Illinois and Missouri also lost power from a storm that created the most significant damage in the company's more than 100 years of service. The storm caused extensive tree damage, broken poles and downed wires in addition to the loss of more than 400 distribution feeder circuits.

Near-hurricane force winds left more than 365,000 PECO customers in the Philadelphia, Pennsylvania, region without power, making it one of the 10 most damaging storms in the company's history.

Canada's Hydro One service area was also struck by a severe storm. Nearly 170,000 customers lost power as a result of high winds, and hundreds of downed trees and lighting caused substantial damage to lines, poles and other hydro equipment.

Canada's Alberta Electric System Operator had to institute a series of 30-minute rotating power outages in different parts of the city in July as a result of hot and humid weather, which increased the demand for electricity.