Mayor Bill de Blasio is urging New Yorkers to stay safe in the summer heat.

He released an advisory Sunday as the city sweltered through the hottest day of the year so far. Monday's temperature is set to reach a stifling 93 degrees, according to the National Weather Service. A heat advisory is in effect until 6 p.m. Monday.

In light of temperatures over 90 degrees through Monday, Mayor de Blasio released an advisory urging New Yorkers to stay safe in the heat.

The high temperatures on Sunday and Monday pose a risk to New Yorkers, namely the sick and the elderly in particular, and the advisory suggests checking in with neighbors. Other recommendations include limiting physical activity, drinking water and using air-conditioning.

Senior centers are acting as cooling centers and the Department of Homeless Services has increased outreach to help get people out of the sun.