Dangerous Heat and Heavy Rainfall into the Weekend
Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >
| NWS Forecast for: Northerly Island to Calumet Harbor IL (LMZ742) Issued by: National Weather Service Chicago, IL Last Update: 308 PM CDT Sat Sep 19 2026 |  |
Late This Afternoon: Southeast winds around 10 kt. Showers likely and slight chance of thunderstorms. Waves 2 to 4 ft. Tonight: Southeast winds 10 to 20 kt becoming north and increasing to 15 to 25 kt late. Showers and a chance of thunderstorms. Waves 1 to 3 ft building to 2 to 4 ft. Sunday: North winds 15 to 20 kt becoming northeast and increasing to 30 kt. Showers and slight chance of thunderstorms in the morning, then chance of showers in the afternoon. Waves 4 to 6 ft occasionally to 8 ft building to 6 to 9 ft occasionally to 12 ft. Sunday Night: Northeast winds to 30 kt becoming east 20 to 25 kt. Slight chance of showers in the evening. Waves 6 to 9 ft occasionally to 12 ft. Monday: East winds 20 to 25 kt becoming northeast to 30 kt. Chance of showers in the morning, then slight chance of showers in the afternoon. Waves 7 to 10 ft occasionally to 13 ft. | |
| Zone Forecast: Northerly Island to Calumet Harbor IL (LMZ742) | |
Visit your local NWS office at: https://www.weather.gov/lot |