Australian Nick Thompson has shown again he is a rising star in long-course triathlon, winning the 70.3 Hobart race.

The women's race went to American Chelsea Sodaro, her first win since claiming the Ironman world championship two years ago in Hawaii.

In four domestic 70.3 or half-Ironman races, Thompson has racked up two wins, a second and a third.

He mastered wet conditions on Sunday, clocking three minutes 54 minutes 10 seconds for the 1.9km swim, 90km cycle and 21.1km run triathlon.

Victorian Mitch Kibby was four minutes behind in second place and Cam Wurf, the best-credentialled local, was hampered by a flat tyre late on the bike but still rounded out the podium.

Spanish star Javier Gomez and top New Zealander Braden Currie led the men out of the water, but did not finish the bike leg because of mechanical problems.

Thompson took the lead midway through the bike leg and maintained it to the finish, while Kibby passed Wurf on the run and beat him by a minute.

"I feel great now that it's over," Thompson said.

"It's a really beautiful course, but it's really testing, testing conditions as well.

"I think it was Cam who said you don't really know where you're at this time of the year after Christmas and New Year's, and I probably wasn't feeling the best I've ever felt, but everybody is probably in the same boat.

"It was more about just keep on going, one step, one pedal stroke."

Sodaro was third out of the water and led the women off the bike - a rarity for her.

She won in 4:18:59, more than four minutes ahead of Australian Grace Thek.

Belgian Hanne De Vet was another three minutes back in third.

"It's a super positive start to my season this year ... last year was tough for me, a lot of ups and downs and I lost some of the joy in my racing, so it's exciting to be finding that again," Sodaro said.

"It feels like a bit of a monkey off my back and a great way to start the Ironman season."