Organizers have predicted testing weather conditions for the yellow jersey contenders during the 18th stage of the race Thursday, a 40.5km time trial.

Announcing periodic rain and strong winds between 30-60km per hour, a statement issued by the local weather office in Annecy said: “There will be significant changes in the weather conditions throughout the day.

“Ideally, it would be best to race the time trial in the morning or midday.”

The statement added that the riders, who start the race against the clock at intervals, faced a headwind for the first 18km until Doussard, where the course turns back on itself and heads back up the eastern side of the lake.

The bulk of yellow jersey contenders will start the race after 1700 GMT, or 1600 local time.

Current race leader Alberto Contador will start last from the field at 1647 local time.