Heavy rain began falling in Leeds about an hour before play was due to start on Saturday, with full covers deployed across the pitch.
Conditions are forecast to improve before lunch, with further downpours predicted later in the afternoon.
When play does start, Australia will resume on 4-116 and with a lead of 142 in the third innings.
Rain is also forecast for late on Sunday and Monday afternoon, although with the pace at which the Test has so far been played a result is still likely.
A win for Australia would give them an unassailable 3-0 lead and wrap up their first series win in England since 2001.
A draw would mean Australia retain the Ashes, although the players have made it clear they are in England with the aim of winning the series.
"It's always about winning a series outright, so that's the goal," captain Pat Cummins said before the Test got under way.
"We want to win one of these last three Test matches.
"We're up for a win. A draw would be good in that it would retain the Ashes but we'll be going after a win."
England enter day three with confidence, drawing on successful chases of 296, 362 and 322 in their last three fourth-innings finishes at Headingley.
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