New York City officials have declared a heat emergency, advising homes and businesses to set their cooling systems to 78 degrees.

Con Edison has asked approximately 89,000 customers in areas including the Bronx and City Island to reduce power consumption to alleviate stress on the electrical grid.

Wholesale power prices in the PJM Interconnection grid, which serves the Mid-Atlantic, reached nearly $2,000 per megawatt-hour as temperatures climbed.