Frazar, who won the St. Jude Classic in June for his first PGA Tour title, closed with an even-par 72 to finish at 9-under 279. Tringale had a 73 to tie for second with Matt Bettencourt.
"There's no better place to be miserable," Frazar said. "When the weather is like this, it's a lot easier to do it here than someplace else."
Frazar also hit his final approach into the bunker en route to a par.
Bettencourt (75) was 12 under after eight holes, but had two double bogeys in his final 10 holes.
"We were all hoping they were going to call us in," Frazar said. "On the sixth hole, half the green was under water. Fortunately, none of our putts were in the litte rivers."
Only three of the 41 pros broke par in the final round played in strong intermittent rain and gusting wind.
Frazar earned $60,000 from the $300,000 purse in the 40th annual event that featured players from the PGA Tour, LPGA Tour, Champions Tour and Nationwide Tour.
After Tringale hit his second shot on the par-5 18th into the front bunker, he missed a 12-footer that would have given him the victory, then missed the short par putt to hand Frazar the title.
"I just looked up and it was left," Tringale said. "There was a lot of rain, but it wasn't as bad as it was supposed to be. When played in a lot of rain in college, but you never really get used to it."
Leta Lindley was the only LPGA player to make the cut. She shot a 76 to finish 3 over.