Right now the southern portion of NJ is seeing the coldest temperatures. Why? Clear skies there have allowed for heat to escape while up north the cloudy conditions act like a blanket trapping the warmer air. Some places in South Jersey saw 40 degrees for highs and are currently at 23 degrees while Netcong saw a high of 30 and is currently at 28 during the same time frame. Now that's why I love meteorology!