Series organiser Dorna announced following Saturday morning's MotoGP qualifying session that the race start times for all three classes will be brought forward by an hour.
The MotoGP sprint race, which had been scheduled for 2pm local time, will now take place at 1pm as a result.
It comes amid the threat of rain and high winds that look set to lash Phillip Island on the final day of the weekend, with gusts of up to 80km/h (50mph) having been forecast.
Additionally, 10-minute warm-up sessions have been added for both Moto2 and Moto3 to allow riders to familiarise themselves with the conditions at full racing speeds. Both the intermediate and lightweight classes had their respective warm-ups axed from the schedule for 2023.
Moto3 warm-up will take place at 8am, with Moto2 following at 8.20am and MotoGP at 8.40am.
The start time for the Moto3 race is now 10am, while Moto2 is slated for 11.15am before the MotoGP sprint at 1pm.
A statement from Dorna said the changes to the race start times had been made "in order to avoid the worst of the weather which is forecast to arrive at some time after 2pm".
The latest changes to the Australian GP schedule follow the decision taken on Saturday to essentially swap the MotoGP sprint and main race on the schedule, with the full-distance encounter now taking place on Saturday at 3.10pm.
It ensures that at least 25 points will be up for grabs at Phillip Island even if the sprint race, which awards 12 points for a win, cannot take place on Sunday.
