WESTMINSTER, Colo. — SPP set a new mark for peak demand Monday, wiping out a record that was less than a week old.

The grid operator’s 14-state footprint met 51.4 GW of demand at 4:44 p.m. CT. That betters the previous mark of 51.1 GW set July 5. (See SPP Sets Demand Record amid Midwest Heat.)

The new mark is expected to be as equally short-lived as the previous record. Staff are projecting demand will hit 53 GW next Monday, when forecasters are expecting triple-digit temperatures and muggy weather as a high-pressure ridge moves from the Rockies to the Plains.

“Summer’s not over,” Bruce Rew, senior vice president of operations, told the Markets and Operations Policy Committee meeting Tuesday.

Rew said SPP would remain in a resource advisory until at least Wednesday, “if not longer.” On Wednesday, the RTO extended the advisory for its entire 14-state balancing authority to Friday at 10 p.m. It said this was necessary “because of the persistence of extreme heat, high electricity use across its region and uncertainty in its wind forecast.”

SPP issues resource advisories when it expects extreme weather, significant outages, and/or wind- and load-forecast uncertainty in its service territory. They do not require public conservation.