The “cold weather advisory” is a new type of advisory for the National Weather Service, replacing the “wind chill advisory,” said Daniel Hartsock, a meteorologist with the National Weather Service in Portland.

Two towns in Sussex County — Walpack and Sandyston — reported overnight low temperatures of -16 degrees between 7 and 8 a.m. Wednesday morning before Walpack dropped a bit more, down to -17 degrees one hour later, according to data from the Rutgers NJ Weather Network, overseen by the state climatologist’s office.

The coldest low temperatures reached on Wednesday was in Great Barrignton, between minus 20 and minus 15 degrees, the post read. Springfield saw temperatures that were 10 degrees warmer – specifically, between minus 10 and minus 5 degrees.

Delaware is under a cold weather advisory. The forecast is calling for dangerous wind chills. Here's what you should know.