The reports were made Monday from weather spotters and have not yet been confirmed by the weather service.
Investigations were to be conducted on Tuesday.
The weather service website says a tornado was seen by weather spotters at 5:32 p.m. about 7 miles northeast of Rochelle in Ogle County.
About four minutes earlier, radar confirmed a tornado near Hampshire in Kane County.
Tornado warnings were issued late Monday afternoon for parts of northern DeKalb County and southern Lee County.