The six-stage Tour was scheduled to start on Tuesday with the 135km first stage in the Barossa Valley, which is currently under threat from the fire.
"If it's a no-go zone for the Barossa, it's a no-go zone - simple as that," race director Mike Turtur told reporters.
"(It's) possibly the cancellation of the stage, depending on the advice from the correct people.
"Any activity in the region that's deemed to be dangerous to the public, then obviously you can't ask people to go into the area.
"It would be crazy to do that."
Fires in the Barossa Valley have threatened lives and destroyed properties as extreme heat and high winds fanned dozens of bushfires across Australia.
The country's south and southeast have been in the grip of a heatwave for nearly a week, with climate experts warning of even hotter and longer spells to come.
If Tuesday's stage is called off, it will be the first instance of a cancellation in the 15-year history of a Tour that takes place in and around Adelaide.
"You just move onto the second stage, everyone is in the same situation," said Australian rider Simon Gerrans, a two-time Tour winner.