A hot day in the saddle awaits TDU field

Conditions will be tough for the Tour Down Under riders as they race from Prospect to the Barossa town of Lyndoch.

The peloton during the People's Choice Classic event at the Tour Down Under (AAP) Source: AAP

 A blast furnace awaits the cyclists in stage one of the Tour Down Under.

The forecast for Tuesday's 130.8km stage from suburban Prospect to Lyndoch in the Barossa is 40 degrees.

They will probably also have a headwind for the stage, which heads north out of Adelaide.

Stage three of the Santos Women's Tour started and finished in Lyndoch on Monday and winner Lizzie Williams was exhausted at the finish because of the oppressive heat.

The heat is always the critical factor in the Tour Down Under, which opens the WorldTour calendar.

The good news for the riders is that Tuesday should be the hottest weather in the six-day race.

While conditions will be humid and in the mid-30s through Wednesday and Thursday, the temperature should be down to the high-20s for Saturday's Queen stage at Willunga.

Australian cyclist of the year Rohan Dennis aims to be the first rider in the tour's 18-year history to win successive titles.

But the BMC team leader will face strong opposition from Orica-GreenEDGE star Simon Gerrans, who has won the race a record three times.

Gerrans is determined to return to top form after last year was ruined by a horror run of crashes.

His young teammate Caleb Ewan is the best sprinter in the field and he is one of the favourites to win stage one.

Team Sky pair Geraint Thomas and Sergio Henao are also contenders.

Another rider to watch is Dennis' compatriot and new teammate Richie Porte.

He finished second overall a year ago, but Porte is deliberately having a slower start to this season because he wants a big result at the Tour de France.

Nevertheless, Porte is one of the best climbers in the field and is a handy plan B for BMC is Dennis does not fire.