MILWAUKEE (AP) - Classes in Wisconsin's largest school district have been canceled because of the bitter cold that's wrapped the Upper Midwest.
Nearly 78,000 students in Milwaukee Public Schools are off Friday, when high temperatures are expected to reach just 2 degrees (negative 16.7 Celsius) with a wind chill of minus 23 (negative 20.5 Celsius).
The wind chill is of more concern because frostbite can occur within minutes.
Wind chill advisories are in effect across a broad swath of the Upper Midwest, where wind chill factors could dip to as low as 50 below zero (negative 45 Celsius) in parts of Wisconsin and Minnesota and to 35 below (negative 37 Celsius) in the Dakotas.
The weather is part of an arctic wave crawling across the region. Forecasters say the numbing cold weather is expected to linger into next week, with even colder temperatures midweek.
Wind chill advisories were issued for a broad swath of the Upper Midwest, where wind chill factors could dip to 40 to 50 degrees below zero (40 to 45 below zero, Celsius) in parts of Wisconsin and Minnesota and to 30 to 35 below (34 to 37 below, Celsius) in the Dakotas.
The deep freeze caused organizers of the Winter Carnival in Minnesota to cancel several events, including Thursday night's parade through downtown St. Paul.
Sioux Falls, South Dakota, has closed its six outdoor skating rinks because of the cold weather.