A potentially record-breaking heat wave is expected to encroach upon most of Texas, Louisiana, and parts of Florida through the weekend, with a heat index of up to 120 degrees possible in some areas.

More than 33 million people were placed under heat advisories by the National Weather Service on Thursday, some of which are scheduled to remain in effect through Friday night.

"It wouldn't be an active summer weather pattern without oppressive heat," the Service noted, adding, "much of Texas and the Deep South will have plenty."

NEAR-100 MPH WINDS, POSSIBLE TORNADOES, RAVAGE SOUTH; VEHICLES 'BLOWN OFF' TEXAS HIGHWAY

Temperatures in southern Texas were gauged at well over 100 degrees by noon Thursday, with Houston reporting a 111-degree heat index, while the nearby Gulf Coast city of Galveston clocked in at 108 degrees.

Houston and Texas' other urban centers are anticipated to bear the brunt of the heat, with index readings anticipated to hit 115 degrees in the coming days. The Dallas-Fort Worth metroplex is expected to see concurrent readings between 105 and 112 degrees. Readings as high as 120 degrees may also be reported along the Gulf Coast.

NORTHEAST FACING WET WEATHER, BELOW AVERAGE TEMPERATURES THIS WEEK

As temperatures rise, a significant spike in energy demand is likely to ensue. The Electric Reliability Council of Texas (ERCOT), which manages 90 percent of the Lone Star State's electrical grid, expects supply to satisfy demand and dismissed concerns of a potential "energy emergency."

Meanwhile, New Orleans reported a morning heat index of 96 degrees on Thursday, with the city's National Weather Service branch quipping, "Dat's some bayou weather right there," in a nod to the Big Easy's local dialect.

In parts of southern Florida, including Miami-Dade and Palm Beach counties, triple-digit temperatures were also reported, with officials warning residents against leaving children and animals outside unattended.

The Associated Press contributed to this report.