PJM Interconnection, the grid operator in 13 Mid-Atlantic States, set a new winter peak demand of 143,826 megawatts on Feb. 20, according to the National Electric Reliability Corporation (NERC). That was nearly 1,000 mw more than the previous peak reached Jan. 7, 2014, during a polar vortex that plunged the nation into a deep freeze.

NERC said at least four large electric utilities in the Mid-Atlantic and Southeast also set peak load records on Feb. 20.

“Throughout these record cold temperatures and peak loads, operators ensured the bulk power system remained reliable through advanced planning and preparation,” NERC said.