Butler, Seneca Valley, Slippery Rock and Karns City school districts announced two-hour delays and modified Kindergarten hours for Tuesday due to cold temperatures.

Portersville Christian School and Cardinal Wuerl North Catholic High School also announced a two-hour delays.

The National Weather Service in Pittsburgh issued a wind chill advisory for Butler County and surrounding areas, which was in effect until noon Wednesday.

Wind chills in some areas were expected to get as low as 15 degrees below zero. The wind chill can cause frostbite in as little as 30 minutes to exposed skin, according to the advisory.

Mars, South Butler, Moniteau, Allegheny-Clarion Valley and Freeport districts are on winter break until Wednesday.