INDIANAPOLIS (AP) – A blast of frigid air that's sent temperatures plunging toward zero across northern and central Indiana has prompted many school districts to cancel classes due to dangerously low wind chills.

Indianapolis Public Schools, one of the state's largest school districts, canceled Wednesday's classes as did many others across the state's northern half, where a daylong wind chill warning was in effect.

Temperatures fell into the single digits across much of the warning area but gusty winds were creating wind chills of between 15 and 20 degrees below zero.

The National Weather Service says temperatures will plummet later Wednesday and the wind chills across the warning area could fall to 25 to 30 degrees below zero through Thursday morning as sub-zero readings envelop all but far southern Indiana.