The National Weather service has Kendall County and the surrounding area under a flood advisory until 11 p.m. tonight.
About a quarter of an inch of rain has already fallen, said the NWS.
The rain, combined with clogged storm sewers and drainage ditches from the snow will "likely result in significant ponding and some minor flooding," said the NWS.
The area is also under a "special weather statement" for "slick roads."
"Untreated and uncleared secondary roads and sidewalks will remain slushy and icy for the next few hours with additional minor glazing likely," said the NWS, which will make for hazardous travel conditions.
The roads are expected to improve later this evening as the temperatures fall.