At 12:56 a.m. on Friday, the National Weather Service released an updated cold weather advisory in effect until 11 a.m. for Franklin, Worcester, Hampshire, Hampden and Middlesex counties. The weather service adds, "Very cold wind chills between 20 and 25 degrees below zero expected." Understanding cold weather alertsCold weather advisory: Be Aware. A cold weather advisory is issued when seasonably cold air temperatures or wind chill values, but not extremely cold values, are expected or occurring. An extreme cold warning is issued when dangerously cold air temperatures or wind chill values are expected or occurring.