The third weather delay of the day turned out to be the last one and 44 players were unable to complete play.
Those with morning tee times had the best of the weather Friday and Haas was one of those. He played a three-hole stretch on the front nine at the Muirfield Village Golf Club in 4-under par, recording an eagle at the par-5 fifth, and posted his 67 despite a bogey at the 18th.
That put Haas at 9-under 135 for 36 holes.
Matt Kuchar, runner-up last week at the Colonial Invitational and trying to become the second multiple winner on the PGA Tour this year, finished the second round at 6-under 138. First-round leader Charl Schwartzel, Bubba Watson and Kyle Stanley were also at 6-under when play brought an end to their day late in their rounds.
Defending champion Tiger Woods also had an early starting time, but did not take advantage of the calmer conditions and wound up with a 2-over 74 that left him at 1-over 145.
Woods three-putted from inside 5 feet at the par-5 15th for a double bogey. There were 45 players ahead of Woods when play was halted.
Rory McIlroy, whose 76 Thursday was his highest opening round ever on the PGA Tour, rebounded Friday to complete 14 holes in 4-under. He was 2-over for the tournament and was in position to survive the 36-hole cut, which was projected to be 3-over.
Haas has won at least once in each of the last three years. His biggest victory came at the 2011 Tour Championship, which gave him the FedEx Cup title and the accompanying $10 million.