Beem says the plane had a cracked windshield, but it was unclear whether it was caused by the lightning strike.
No injuries were reported.
Passenger Nancy McCartan tells WREX-TV that she heard a "very loud crash noise and a flash." She said a flight attendant told passengers the aircraft had been struck by lightning, and the pilot reassured them that everything was OK.
Passengers were bused to O'Hare once the Embraer E145 landed.
The Federal Aviation Administration is investigating.