The extreme heat is here and is expected to stay through the weekend with temperatures increasing to dangerous levels.

The sweltering heat is affecting New Yorkers and Americans in major cities across the Northeast and Midwest. 

Officials say New York City could see numbers skyrocket to triple digits. 

Mayor Bill de Blasio declared a state of heat emergency ahead of the weekend, directing large office buildings, 100 feet tall or more, to conserve energy by keeping their thermostats at or above 78 degrees. 

MORE: News 12 Weather Center

Cooling centers are open across the Bronx and all five boroughs. Places like community centers, libraries, senior centers and some NYCHA facilities are open for cooling down.

The Office of Emergency Management and the Health Department are advising people to pay attention to the signs of heat-related health problems. The offices say to keep cool and hydrated, never to leave children unattended in cars and to apply sunscreen -- or stay out of the sun altogether.

The Administration for Children's Service is reminding people with children to be very careful. They say to keep your children cool and hydrated. If  they're going to be in the sun, make sure they apply sunscreen. And children are advised to stay away from sugary drinks.

Officials also ask residents to make sure to check on their elderly neighbors and loved ones.

Mayor de Blasio is expected to talk more about the summer heat at a press conference at 2 p.m.

Click here to find a cooling center.