Flash Flood Warning issued September 20 at 2:12AM CDT until September 20 at 8:00AM CDT by NWS Chicago IL
Issue date: 2026-09-20T07:12+00:00
FFWLOT The National Weather Service in Chicago has issued a * Flash Flood Warning for... Southern De Kalb County in north central Illinois... Northern La Salle County in north central Illinois... Lee County in north central Illinois... * Until 800 AM CDT. * At 212 AM CDT, Doppler radar indicated thunderstorms producing heavy rain across the warned area. Up to 3 inches of rain have fallen. The expected rainfall rate is 1.5 to 2.5 inches per hour. Additional rainfall amounts of 1 to 3 inches are possible in the warned area. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar indicated. IMPACT...Rapid-onset flooding of creeks, streams, drainage ditches, streets, underpasses, low-lying areas, and other poor drainage areas. * Some locations that will experience flash flooding include... Sandwich, Mendota, Amboy, Sheridan, Shabbona, Lake Holiday, Hinckley, Somonauk, Earlville, Waterman, Serena, Leland, Paw Paw, Sublette, Woodhaven Lakes, Millington, Lee, Compton, Troy Grove, Nelson, West Brooklyn, Harmon, Triumph, Prairie Center and Lee Center.
Flood Advisory issued September 20 at 12:16AM CDT until September 20 at 3:15AM CDT by NWS Chicago IL
Issue date: 2026-09-20T05:16+00:00
* WHAT...Flooding caused by excessive rainfall is expected. * WHERE...Southern De Kalb County in north central Illinois... Northern La Salle County in north central Illinois... Lee County in north central Illinois... * WHEN...Until 315 AM CDT. * IMPACTS...Creeks and streams may rise out of their banks. Roads and streets may be flooded. * ADDITIONAL DETAILS... - At 1213 AM CDT, Doppler radar indicated heavy rain due to training thunderstorms. Minor flooding is ongoing or expected to begin shortly in the advisory area. Up to 2 inches of rain have fallen. - Additional rainfall amounts in excess of 1 to 3 inches are possible over the area overnight which may result in additional flooding. - Some locations that will experience flooding include... Sandwich, Mendota, Amboy, Sheridan, Shabbona, Lake Holiday, Hinckley, Somonauk, Earlville, Waterman, Serena, Leland, Paw Paw, Sublette, Woodhaven Lakes, Millington, Lee, Compton, Troy Grove, Nelson, West Brooklyn, Harmon, Triumph, Prairie Center and Lee Center. - http://www.weather.gov/safety/flood
Flood Watch issued September 19 at 8:23PM CDT until September 20 at 7:00AM CDT by NWS Chicago IL
Issue date: 2026-09-20T01:23+00:00
* WHAT...Flash flooding caused by excessive rainfall continues to be possible. * WHERE...Portions of Illinois, including the following areas, Boone, Central Cook, De Kalb, DuPage, Kane, Kendall, Lake IL, Lee, McHenry, Northern Cook, Northern Will, Ogle, Southern Cook and Winnebago and northwest Indiana, including the following areas, Lake IN and Porter. * WHEN...Until 7 AM CDT Sunday. * IMPACTS...Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. Underpasses may be flooded. Roads and streets may be flooded. * ADDITIONAL DETAILS... - Another round of showers and thunderstorms is expected late this evening and overnight. Swaths of heavy to very heavy rainfall with 2+ inch per hour rainfall rates are likely to occur within the watch area and may result in areas of flash flooding and cause rapid rises on area rivers, creeks, and streams. - http://www.weather.gov/safety/flood
