Parts of Ohio, New York and Pennsylvania have experienced power outages during this week’s heat wave, leaving tens of thousands of residents without electricity and air conditioning amid sweltering temperatures.
These outages show the pressure that extreme heat is placing on power grids across the country: With more people using air conditioning during a heat wave, regional utilities can get overwhelmed as demand for electricity outpaces supply. The heat can also reduce the effectiveness of the equipment at power plants and transmission lines as materials are distorted by high temperatures.
According to a 2025 report from the North American Electric Reliability Corporation, an organization that develops standards for the region’s power system, states in the Midwest, the South and New England are among those more vulnerable to potential power disruptions when there are “above-normal” heat conditions.
Scientists also note that heat waves have grown more frequent and intense as a byproduct of human-induced climate change, meaning power grids will experience more strain in the future.
Between 2014 to 2023, the number of heat season power outages increased by 60% compared to the 2000 to 2009 timeframe, per a report from Climate Central, a nonprofit that researches the effects of climate change.
Such outages can exacerbate the health risks of extreme heat, which is already the deadliest form of extreme weather in the U.S. Elderly people, children, pregnant people and people with chronic conditions are particularly vulnerable to conditions like heat stroke and exhaustion. In Maricopa County, Arizona, three-quarters of people who died indoors from heat-related factors in 2023 had a non-functioning air conditioner, The Associated Press reported.
Policymakers have urged people to conserve power and raise their thermostats to help prevent potential blackouts in the near term.
On Tuesday, New York Gov. Kathy Hochul called on residents to keep their air conditioning set to 76 degrees and to reduce the use of appliances as the region’s electric grid neared capacity.