I don't recall ever seeing a published delay anywhere near this long, where the airport isn't closed.

Chicago O'Hare Intl (KORD) is currently experiencing:
arrival delays for airborne aircraft an average of 37 minutes
departure delays of 1 hours 46 minutes to 2 hours (and increasing) due to thunderstorms
inbound flights delayed at their origin an average of 5 hours 41 minutes due to thunderstorms