A wind chill warning has been issued for the entire Chicago area, leading to school closures and flight cancellations across the region. The National Weather Service predicts that the warning will remain in effect until Tuesday at noon, with potential wind chills dropping as low as 40 degrees below zero.

Various counties in Illinois and Indiana are under wind chill advisories. Kankakee and eastern Will counties in Illinois, as well as Lake and Porter counties in Indiana, are under a wind chill warning until Monday at noon. Additionally, a wind chill advisory will be in effect for these counties until Wednesday at 9 a.m.

McHenry, Lake, DuPage, Cook, DeKalb, Kane, LaSalle, Kendall, Grundy, and northern and southern Will counties in Illinois will experience a wind chill warning until Tuesday at noon. A wind chill advisory for these counties will last until Wednesday at 9 a.m.

Newton and Jasper counties in Indiana are also under a wind chill warning until Monday at noon.

As a result of the extreme cold conditions, multiple schools have announced closures through Tuesday. While many public schools were already closed on Monday for Martin Luther King Jr. Day, others have canceled classes or shifted to e-learning due to the dangerously low wind chills, which can reach as low as 35 degrees below zero.

Flight disruptions have also been reported, with over 300 cancellations as of early Monday morning. Additionally, Metra's BNSF train line temporarily stopped its services due to frozen switches near Union Station. The agency expected to resolve the issue within two hours, but no specific timing was provided.

The National Weather Service advises residents to avoid outdoor activities if possible. In case of necessary outside exposure, it is crucial to wear protective clothing to minimize the risk of frostbite, as wind chills can cause inclement conditions in as little as 10-30 minutes.

Once the wind chill warning expires, a wind chill advisory will be in place until Wednesday at 9 a.m. in several counties. However, it is not until Wednesday morning that wind chills are expected to rise above -10 degrees.

The wind gusts are projected to persist throughout the upcoming days. Dangerously cold temperatures and wind chills will continue until mid-week, with slightly "milder" conditions forecasted for Wednesday and Thursday. However, another bout of Arctic cold weather is anticipated towards the end of the week.

Residents in the Chicago area are urged to stay updated on weather alerts, follow safety guidelines, and take necessary precautions to ensure their well-being during this period of extreme cold.