Hoffman crossed the line almost 20 minutes ahead of second place finisher Maik Twelsiek while Kessler won the race ahead of the women's finisher Jessie Donovan by about 25 minutes.
"Let me tell you, that was a day out there," Kessler said. "The swim — I thought I was going to end up on an episode of 'Lost.' Everyone had to deal with the tough conditions out there. The theme of day was to stay under control because it's easy to blow up on this course."
"This is the hardest race I've ever done," Hoffman said. "This is hands-down the hardest thing I've ever done."
Next year Ironman St. George will be shortened to a IM 70.3 race. This year's brutal hot and windy conditions may be one reason the race did not sell out for a second year in a row.
Ironman St. George results
Top 5 Professional men
1. Ben Hoffmann (USA) 9:07:04
2. Maik Twelsiek (GER) 9:25:58
3. Axel Zeebroek (BEL) 9:35:33
4. Thomas Gerlach (USA) 9:49:00
5. Matthew Sheeks (USA) 9:52:03
Top 5 Professional women
1. Meredith Kessler (USA) 10:12:59
2. Jessie Donovan (USA) 10:37:30
3. Uli Bromme (USA) 10:53:20
4. Gillian Clayton (CAN) 11:15:38
5. Erin Spitler (USA) 11:16:42