A blistering heat wave is spreading across the US with temperatures reaching well above 100 degrees in many regions.

Las Vegas reached 105.8 F (44 C) on Wednesday.

South Dakota, Texas, and Oklahoma all hit 112.2 F (44 C).

The small towns of Wichita Falls, Texas, and Mangum, Oklahoma recorded scorching temperature readings of 115 F (46 C).

"Excessive Heat Warnings and Heat Advisories are in effect this morning throughout 28 states, stretching from California to New Hampshire,” tweeted the National Weather Service (NWS) Weather Prediction Center. "High temperatures into the 90s and 100s will increase the risk of heat related illnesses.”

The NWS says the heat advisories and excessive heat warnings will affect nearly 110 million Americans, with more than 60 million residents anticipated to see triple-digit heat over the next week.

The Southwest and south-central parts of the US are expected to be hit hardest, with highs topping 100 degrees (37 C) in much of Texas and Oklahoma.

The NWS says the combination of hot temperatures and dangerous heat indices add up to "another brutal day."

Dallas, Austin, San Antonio, Oklahoma City, and Tulsa could approach 110 degrees in the upcoming days.

“Another day of exceptional heat lies ahead with triple-digit highs forecast for all of North and Central Texas,” wrote the NWS in Fort Worth.

Houston, which is closer to the Gulf of Mexico's moist air, will experience the saturation of humidity with temperatures reaching between 98 and 102 degrees.

“Today will be a scorcher no matter where you are,” wrote the NWS in Houston.

Heat alerts are also hitting the Northeast, with New York, Philadelphia, and Boston expecting unusually high temperatures reaching 100 F (37 C) in some areas.

But the unrelenting heat and humidity are not expected to let up anytime soon, especially in cities such as Houston, Dallas, Austin, Oklahoma City, Tulsa, and Little Rock, Arkansas, where triple-digit numbers are set to last for at least the next week.

"Hot, muggy, and basically ‘swimming in the air’ conditions," said the NWS in Little Rock. (Anadolu Agency)

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