National Weather Service United States Department of Commerce


Two rounds of thunderstorms produced significant rainfall across portions of northern Illinois on Monday August 9th. A morning round of storms produced heavy rainfall across parts of northern Illinois, especially across portions of southern Boone and McHenry Counties where up to 3 to 4 inches of rain fell causing instances of urban and small stream flooding. 


The afternoon and evening thunderstorms were mainly supercells that produced numerous tornadoes, some of which caused noteworthy tree and structural damage in portions of Ogle, DeKalb, and Kane Counties. NWS Chicago issued a total of 13 Tornado, 2 Severe Thunderstorm, and 3 Special Marine Warnings between 3:00 PM and 10:15 PM. A total of 10 tornadoes were confirmed in the NWS Chicago County Warning Area (CWA). 

Preliminary Event Summary Graphic
nws logo Media use of NWS Web News Stories is encouraged!
Please acknowledge the NWS as the source of any news information accessed from this site.

Additional recaps can be found on the NWS Chicago Past Events Page
nws logo