The right-arm medium pacer has made himself unavailable so he can attend his sister's wedding.
Orthodox off spinner Will Somerville replaces McSkimming in the only change to the side that drew with Northern Districts in Invercargill last week.
Otago coach Mike Hesson acknowledged his bowling attack would be under strength for the vital game.
‘‘We're obviously a stronger side when Warren plays, and it was a very hard decision for Warren to make, but these things happen,'' he said.
‘‘It is a very important event in Warren's life and we certainly understand that.''
Otago desperately needs a win to stay in touch with the front-runners. Wellington leads the competition with 24 points from Auckland and Canterbury, who are both on 18 points.
Otago has eight points from five matches and will need at least two outright victories in its remaining three matches to make the final.
McSkimming is one of Otago's more experienced players and has had a reasonable season taking 13 wickets at an average of just over 30 runs.
Bradley Scott has been Otago's best performed seamer with 15 wickets at 24.60. But fast bowler James McMillan has been struggling.
Hampered by a hamstring injury early in the summer McMillan has shortened his run up in an attempt to reduce his susceptibility to muscle strains and is yet to hit his straps.
In three first-class matches McMillan has taken just five wickets at more than 60 runs apiece.
‘‘I actually think he has been bowling quite well, even though he has not got a lot of wickets,'' Hesson said.
‘‘I think James is frustrated he hasn't taken the wickets he'd like. But we are certainly confident he adds another dimension to our attack.''
Against Northern Districts in Invercargill last week Hesson said the bowlers were not as disciplined as they needed to be and he expects them to bowl tighter lines and hit a better length, especially with the new ball. All-rounder Sam Wells and Somerville will compete for the final spot in the starting XI.
Somerville has been unlucky not to play this summer. He has been the victim of an Otago lineup which is well-served with off spinner Nathan McCullum and part-time leg spinner Aaron Redmond, who both bat in the top six.
The tall right-hander gives the ball a decent tweak and had a good day against England during a two-day warm-up match in Dunedin last month.
Somerville took three for 73 from a 20-over spell, claiming the scalps of Owais Shah, Tim Ambrose and Philip Mustard.
‘‘At this stage, Will is our next best bowling option and we see it as quite an attacking move,' Hesson said.
The 23-year-old has played three first-class matches for Otago and taken five wickets.
Wellington is down on firepower with Matthew Bell, Stephen Fleming, Mark Gillespie and Jeetan Patel all on national duty.
In-form all-rounder Grant Elliott has been released from the Black Caps test side to play. But Wellington has an inexperienced look, with Josh Brodie on debut and Fraser Quarterman BJ Crook and Stephen Gellatly having played just four first-class games between them.
