A frost and freeze are likely Monday night for most of the area as temperatures drop into the upper 20s and lower 30s, so bring in or cover sensitive plants and flowers.
The National Weather Service has issued a freeze warning for Schuylkill, Carbon and Monroe counties into the Poconos into Tuesday morning.
A frost advisory is in effect for Berks, Bucks, Chester, Lehigh, Montgomery and Northampton counties in Pennsylvania and Hunterdon and Warren counties in New Jersey.
Tuesday will feature a mix of clouds and sun with highs in the lower and middle 60s.
Much warmer air will arrive for the middle of the week.