The northern lights are visible in the area.
Video from Richmond in far northern Illinois showed the celestial spectacle.
ABC7 has also received more videos and photos from viewers across the entire Chicago area showing the aurora.
The phenomenon is caused by a severe solar storm that could stress power grids even more as the U.S. deals with major back-to-back hurricanes, space weather forecasters said Wednesday.
The National Oceanic and Atmospheric Administration issued a severe geomagnetic storm watch for Thursday into Friday after an outburst from the sun was detected earlier this week. Such a storm could temporarily disrupt power and radio signals.
The storm also may trigger northern lights as far south in the U.S. as the lower Midwest and Northern California, though exact locations and times are uncertain, according to NOAA. Skygazers are reminded to point their smartphones upward for photos; the devices often can capture auroras that human eyes cannot.
May's solar storm produced dazzling auroras across the Northern Hemisphere and resulted in no major disruptions. The sun is near the peak of its current 11-year cycle, sparking all the recent solar activity.
The Associated Press contributed to this report.