Tom Kite, Keith Fergus and Bobby Walzel share third place at 3-under-par 68.
Weibring got off to a quick start and hit a 4-iron to eight feet for a birdie at the par-3 second. He added another birdie at the par-4 third after his approach stopped within 30 feet of the hole.
The 50-year-old kept on rolling with a birdie at the par-4 seventh and pitched his third shot to 4-feet for a birdie at the par-5 ninth to go out in 31.
Weibring made it two in a row with a birdie at the par-4 10th and hit a 6-iron to 25 feet at the par-4 12th.
Weibring drained the birdie putt and parred his way in to secure the outright lead.
'I feel like I've been playing well coming in,' said Weibring, who captured last year's SAS Championship. 'I expected to do good here. The course is in fabulous shape.'
Wargo played the back side first and roped a 3-iron within 10 feet of the cup at the par-5 11th. He ran home the eagle putt but gave a shot back with a bogey at the 13th.
The 61-year-old tallied consecutive birdies from the 15th before dropping a shot at the 17th.
Wargo found trouble again with a bogey at the second, but recovered well over his closing holes.
He picked up a birdie at the fifth and played a wedge to eight feet for a birdie at the seventh.
Wargo added a birdie at the ninth to take second place alone and like Weibring had praise for the course.
'You've got to hit fairways on this course,' said Wargo. 'It's in good shape.'
Tom Watson collected two birdies en route to a bogey-free round of 69. He was joined by Allen Doyle, Bruce Summerhays, Jay Sigel, Bobby Lincoln and Gibby Gilbert.
Defending champion Don Pooley struggled in the opening round with an 80.