Con Edison had to cut power to some 30,000 New York City customers on Sunday night, most of them in the Brooklyn borough.

As of 10:30 PM Eastern time, the outside temperature was still 87 degrees. The move to cut power was announced by Mayor Bill de Blasio, allegedly so that Con Ed could “make repairs and prevent a bigger outage.”

The move comes as soaring temperatures during the day caused sporadic blackouts throughout the sweltering city and follows a massive Manhattan blackout several days prior.

“I just spoke to Con Ed’s president about tonight’s outages,” the mayor said. via Twitter.“Their system in parts of Brooklyn is under severe strain and some equipment has failed…Con Ed is taking 30K customers in Brooklyn, including Carnarsie, Mill Basin and Flatbush, temporarily off power so it can make repairs and prevent a bigger outage …. @NYPDnews, @FDNY and @NYCEmergencyMgt are all adding personnel on the ground across that part of Brooklyn to respond to emergencies and keep people safe.”

Con Ed also said it would reduce power in other parts of the city. Residents in Queens and Bronx also reported outages.

“City agencies are working with Con Ed to resolve this as quickly as possible,” de Blasio tweeted. “In the event of an emergency, contact 911.”

“It’s still above 90 and I know there are a lot of hot and frustrated people out there, not just in Brooklyn but in parts of Queens and the Bronx,” the mayor said. “Con Ed is working to restore power and City agencies are working to help speed up restoration in every way we can.”