Sweltering temperatures lingered Sunday in a large swath of the central U.S., causing misery from the Gulf of Mexico to the Great Lakes.

Record high temperatures were recorded in Texas and other states. People were told to chug extra water while mowing lawns or exercising outdoors, and to check on neighbors to ensure air conditioning is available. The extreme heat prompted Texas’ electric power grid manager to ask residents to voluntary conserve power for three hours on Sunday night.

“These high temperatures can impact our friends, families, and neighbors who may live alone, especially if they limit their use of air conditioning,” Sarah Russell, commissioner for the St. Louis Emergency Management Agency, said in a statement. “We urge everyone to stop and visit loved ones to ensure they are healthy and well during this extreme heat.”

The Dallas-Fort Worth area was expected to reach 110 F (43.3 C) Sunday after hitting 108 F (42.2 C) Saturday, said Sarah Barnes, a meteorologist with the National Weather Service. The record high for those dates was 107 F (41.7 C), set in 2011.

The area is not cooling off enough at night, Barnes said. “That’s really going to contribute to an increased risk of heat-related illnesses,” Barnes said Sunday. “That’s the main concern when it comes to people and the heat.”

The Electric Reliability Council of Texas, or ERCOT, on Sunday asked the state’s 30 million residents to voluntarily reduce power use from 7 p.m. to 10 p.m. CDT because of “extreme temperatures, continued high demand and unexpected loss of thermal generation.”

ERCOT’s request for voluntary power conservation was the second such request in the past three days. The agency said it was not in emergency operations. Many residents still view the power grid nervously more than 2.5 years after a deadly winter blackout.

The heat wave causing misery this weekend is just the latest to punish the U.S. this year. Scientists have long warned that climate change, driven by the burning of fossil fuels, by deforestation and by certain agricultural practices, will lead to more and prolonged bouts of extreme weather, including hotter temperatures.