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.

CHICAGO — National Weather Service officials issued a cold weather advisory in effect until 2 p.m. Tuesday for portions of central, east central and northeast Illinois as well as northwest Indiana. Officials said dangerously cold wind chills may reach as low as 28 below zero causing frostbite to those exposed to the frigid temperatures in as little as 30 minutes.

Another arctic cold day with single digits is ahead for the Chicago area. Cold weather advisories remain in effect until 2 p.m. on Tuesday and extreme cold warnings for western suburbs last until noon.

A cold weather advisory has been extended across the entire Chicago area, with warmer temperatures slowly creeping into the forecast.