Overnight storm halts US PGA's National
At least five people were killed and hundreds of thousands were still without power on Saturday.
The US PGA Tour issued a statement saying winds in the range of 70-80 mph (112-128 km/h) were reported in the area near Washington.
"There are trees and tents down all over the course and roads leading to the course. Clean-up has begun. Electricity is out at the course," the PGA said, adding that fans and volunteers would not be allowed on the course on Saturday.
Along with downed branches around the course, a 75-foot (22m) tree fell on the fairway of the 14th hole and many of the wooden signs identifying the holes were blown down.
As the extent of the damage became clear, PGA Tour officials first said they weren't sure play would go ahead Saturday, but the third round eventually got underway at 1pm (17:00 GMT).
Overnight leader Hunter Mahan, who had a 36-hole total of seven-under 135, was to tee off at 3:10pm (19:10 GMT). He held a two-shot lead over Brendon de Jonge, Jimmy Walker and Robert Garrigus.
Tiger Woods kept himself in the hunt Friday with a 68 that left him five off the lead.
Although fans were barred, Mark Russell, the PGA Tour's vice president of rules and competition, told the Washington Post that players would be safe.
"Inside the ropes is going to be fine," Russell said. "The periphery is a mess."