Tournament officials have indicated that it is unlikely the first round will be completed today, causing split opening rounds at the championship.
As at 10.00am local time the conditions remained unchanged, however, PGA officials were optimistic the fog would burn off once the morning progresses.
With eight of the holes at Whistling Straits playing along Lake Michigan and some of the most intimidating bunkers, play will not resume until players can see tee to green on all holes.
A number of Aussies have been hampered by the delay with Jason Day and Stuart Appleby amongst the first of the groups that were scheduled to start this morning. Day was in the first group off the 10th this morning due to start at 7.00am.
Geoff Ogilvy, Marc Leishman and Michael Sim also have morning tee times.