The National Weather Service recorded intense precipitation across Chicago and its western suburbs overnight into Sunday, September 20, 2026. Official measurements show 1.74 inches of rain fell in Chicago’s Cook County, while a partial report from Burr Ridge indicated one inch of rain.
Following the rainfall, the Weather Service issued multiple flood warnings for rivers throughout the Chicago area. In addition, advisories were released for several creeks that could experience elevated water levels as runoff moves downstream. The alerts cover both the city proper and outlying communities that lie within the watershed of the region’s major waterways.
The flood warnings target water bodies that have shown rapid rises in response to the recent storm. Local authorities are monitoring river gauges and creek flow rates to assess potential impacts on roadways, bridges, and low‑lying neighborhoods. Residents in affected zones have been advised to stay aware of changing conditions and to heed any further instructions from emergency management officials.
The weather event marks a notable increase in rainfall for the weekend of September 19‑20, prompting the National Weather Service to activate its standard flood response protocols. While the rain totals are within the range of seasonal storms, the concentration of moisture over a short period heightened the risk of localized flooding, leading to the issuance of the current warnings and advisories.