Weibring shot a 5-under 67 for a three-day total of 18-under 198. Haas had a 9-under 63.
Mitch Adams also shot a 63 to finish one shot back at 16-under, his best finish in three years as a professional. Local favorite John Harris, from Edina, Minn., shot 66 to also finish at 16-under.
Tom Jenkins and Jim Thorpe finished at 15-under. Thorpe eagled the last hole and Jenkins made a 53-foot birdie.
Weibring used smart course management on the final hole, a 582-yard par-5. His drive landed on a downhill slope, so he played it safe by hitting left of the water guarding the green, pitched the ball to about 10 feet and made the putt.
Entering the day with a one-shot lead, Weibring was 15-under through the 15th hole when Haas finished his round at 17-under.
Weibring, who finished sixth and eighth the last two years, then birdied the par-4 16th and put his tee shot at the par-3 17th about 3 feet from the hole.
Haas, whose round included a 180-yard eagle on the 15th hole, began the day five shots behind Weibring, but quickly moved into contention by shooting 4-under on the front side. He also birdied Nos. 12, 14 and 18.
Playing in the group in front Haas, Chip Beck, who finished at 12-under, also eagled the 15th hole. His shot was from 158 yards.
Adams, who had a 65 in Tuesday's qualifier to get into the tournament, birdied the first four holes to get to 11-under, and finished the front side with a 6-under 30, the lowest 9-hole score in the seven years the tournament has been played at the TPC Twin Cities.
In his third year as a professional, and first year on the Champions Tour, Adams birdied Nos. 11, 16 and 18 on the back side, the last after hitting his 5-wood about 260 yards off the grandstand and back onto the green, the farthest he said he's ever hit that club.