PJM Interconnection, the biggest U.S. electric grid operator, extended a hot weather alert on Wednesday for the western region of its operational zone till Aug. 24, as scorching heat and humidity ramp up demand for power usage.

Temperatures in the region are expected to reach mid-to-upper 90 degrees Fahrenheit (32.2°C), with high humidity. The grid oversees supply in a 13-state region, managing and paying on-call generators to keep power systems running.

The grid expects to serve an overall forecasted load of around 128,000 MW on Wednesday and 131,000 MW on Thursday, still below its current peak demand of 148,000 MW for this summer, hit on July 27.

The all-time recorded peak electricity demand on PJM was 165,563 MW in August 2006.

"PJM is also coordinating with its neighboring grid operators as other regions experience excessive heat and ongoing high electricity demand," it said in a release dated Tuesday.

Power demand in Texas and other U.S. central states was on track to hit record highs this week.