Jermaine Johnson gave the Owls the lead on 65 but within three minutes Billy Jones had equalised direct from a free-kick before another set-piece by David Noble secured Exeter a come-from-behind win with six minutes remaining.
Wednesday's city rivals Sheffield United moved up to third, within a point and with two matches in hand, after a comfortable win over Wycombe.
Will Hoskins, Ched Evans and Kevin McDonald all scored in the final 24 minutes.
The only other match in the division to survive the big freeze - Hartlepool at home to Bournemouth - finished goalless.




 





