Frigid air that forced many schools to close for the day also is causing delays and closings tonight and into tomorrow.
While Friday traditionally is a big night for boys' high school basketball, many games, including all of those in the Pittsburgh City League, have been postponed because of the cold. Other community activities also have been called off.
See the latest information about school and community closings and delays on KDKA.com, the Post-Gazette's news partner.
The National Weather Service has issued a wind-chill advisory until noon tomorrow. The dangerously cold air coupled with strong winds could mean wind chills of 25 degrees below zero.
By noon today, the temperature at Pittsburgh International Airport had climbed from minus 7 to zero, headed toward a high of about 5 degrees. Though lows tonight could reach about 4 below zero, expect a rebound tomorrow to the upper teens or low 20s. A light accumulation of snow is likely tomorrow night and Sunday.
To put into perspective how cold it is in Western Pennsylvania, consider these temperatures from noon (Pittsburgh time) at other locations: Barrow, Alaska, 0; Portland, Maine, 13; Moscow, Russia, 29; Oslo, Norway, 19; and Reykjavik, Iceland, 34.