The Wildcats improved to 16-5 overall and 11-2 in the Big Sky.
"Shoot, I want to play perfect," said coach Randy Rahe. "But we're getting better. … We're getting better defensively."
Weber State limited Southern Utah to a season-low 29 percent shooting, including only 6 for 24 in the second half.
Thunderbirds coach Nick Robinson was unhappy how his team responded to the Wildcats' pressure.
"Obviously Weber was more physical than we were," he said. "They were tougher than we were and, defensively, took us out of some of our sets. …
"A lot of credit goes to Weber. But we just have to get mentally tougher and physically tougher in order to compete."
Jackson Stevenett scored 24 points and Damon Heuir added 18 for Southern Utah. In the second half, however, they combined to shoot only 3 for 13.
"Stevenett and Heuir are good players," Rahe said. "They have total freedom … and they are hard to guard. But I thought we did a better job in the second half."
Weber owned a 39-33 lead before it broke the game open just after halftime. Over a 101/2-minute span, the Wildcats outscored the Thunderbirds, 19-5.
Jordan Richardson scored eight points during the run and Weber's defense forced Southern Utah to miss 10 of 11 shots.
SUU also committed three turnovers as Weber State increased its stranglehold on second place in the Big Sky.
Meanwhile, Southern Utah had a five-game winning streak snapped. The Thunderbirds slipped to 10-13 overall and 8-6 in the conference.
"The Big Sky is a tough, physical league," Robinson said. "We found out the second-best team in this league right now is tougher than we are. So we have some improvements to make."
Said Richardson, who finished with 15 points, "We knew they had won five in a row. … We were ready for them."
Storylines Wildcats take down T-birds
R Davion Berry scores 21 points to lead Weber State over Southern Utah.
• Leading 39-33, the Wildcats break the game open with a 19-5 run early in the second half.
• Jackson Stevenett scores 24 points for SUU, which has a five-game winning streak snapped.