Australia Weather News

South Australia is facing two days of temperatures in the 40s, with total fire bans imposed for many parts of the state and the extreme weather forcing changes to the Tour Down Under cycling.

The mercury is tipped to reach 41 degrees Celsius in Adelaide on Thursday and Friday, so TDU organisers said stage 3 of the race would be shortened and a public bike ride cancelled.

Stage 4 scheduled for Friday will start one hour earlier and a community challenge that attracts thousands of amateur cyclists, also scheduled for Friday, has been cancelled.

Event organisers said all participants will have their registration fee refunded.

Fire authorities said the danger level was rated as extreme for the Mount Lofty Ranges and Lower South East districts for Thursday and a severe rating had been declared for seven other districts.

Country Fire Service duty commander Phil McDonough said the danger level meant that if a fire started it might prove difficult for firefighters to control in the conditions.

"We're calling for everyone to look at the CFS website and stay informed throughout the day in case a fire starts near you," he said.

"Know where you are at all times and ensure you have at least two exits from an area if you need to escape a fire."

The CFS was mindful of spectators and competitors involved with the Tour Down Under, he said.

"The CFS has staff in the Tour Down Under operations centre to inform organisers of any fire threat, however we also need those spectators along the route to stay alert by taking notice of surroundings," he said.

He advised spectators to take additional care when they parked their vehicles along the race route, as a hot exhaust pipe could ignite vegetation.

"The CFS encourages people to avoid driving a vehicle across paddocks of long, dry grass and avoid parking in vegetation on roadsides and paddocks," he said.

Fire bombers and helicopter ready

CFS chief officer Greg Nettleton said specific firefighting resources were on the ready for the TDU if required.

"We've got resources allocated to the Tour Down Under. We've got a couple of [aerial] bombers earmarked specifically for the Tour Down Under and a helicopter that's there for every day of the TDU," he said.

With temperatures in the 40s forecast along the entire route, organisers said the Glenelg to Victor Harbor stage would be cut back by 26 kilometres.

"We consulted with rider representative Adam Hansen and with our chief commissaire and both agreed it would be sensible to shorten the stage distance," Tour director Mike Turtur said.

A family ride event has been cancelled and entry fees will be refunded, Events South Australia executive Hitaf Rasheed said.

"We know there will be disappointed participants, however safety is our priority and our extreme weather safety plan was developed with that in mind," she said.

Australian cyclist Caleb Ewan wears the leader's ochre jersey heading into the TDU third stage, after he crossed the line first on day two of racing.