Extreme heat sweeps through central US, straining power grids

Extreme heat will grip the central US from the Rocky Mountains to the Mississippi River before spreading to the Gulf Coast through the rest of the month, straining regional power grids.

Heat warnings and advisories stretch from Montana to Texas, with Dallas expected to hit 38C (100F) on Saturday and remain above that level through at least Wednesday, according to Bloomberg Saturday.

With humidity, it could feel as hot as 42C (107F). Another heat zone is affecting Southern California and Arizona, where Phoenix could reach 47C (117F) on Saturday.

"It's a pretty persistent pattern," Bob Oravec, a senior branch forecaster with the US Weather Prediction Center, said. "In some form it stays in place through next week. It changes every day a little bit, but pretty much remains through the end of the month."

The prolonged heat is expected to increase electricity demand across parts of 20 states, while weaker winds under the high-pressure system could reduce wind power generation.

On Saturday, 89 daily heat records could be tied or broken, with another 229 overnight temperature records also at risk. Rapid City, South Dakota, may reach a record 41C (105F) on Sunday.

High overnight temperatures add to energy demand by limiting natural cooling and can pose risks to people, animals, and crops.