The National Weather Service Chicago, headquartered in Romeoville, Illinois, at Lewis University, is responsible for monitoring weather conditions across 23 counties in Northern Illinois, the Chicago metropolitan area, and Northwest Indiana. Its origins date back to October 15, 1870, when the Army Signal Service established the region's first federal weather office in Chicago, which later expanded its forecast area to the Rocky Mountains in 1894. As one of only two NWS offices in Illinois, it issues local forecasts and severe weather warnings for the region. The office also operates 11 NOAA Weather Radio stations, including KWO39, which serves marine interests on southern Lake Michigan and carries severe weather alerts for several counties. These stations provide critical weather and hazard information to a wide swath of Illinois, Indiana, and Wisconsin, ensuring public safety across the area.