Showers caused play to be abandoned early on the fourth day and they continued through to Monday morning, forcing a scheduled early resumption to be cancelled.
Australia need just six more wickets to win the match and regain the Ashes.
Complicating matters further was a damp spot on the pitch, just outside the popping crease at the southern end, with WACA ground staff working furiously with leaf blowers to try to dry it out.
It was unclear how the water got through the covers onto the pitch, although there was some suggestion it happened when strong winds lifted them up.
Match officials were confident the problem would be resolved once the rain stopped, but no time had been set for the resumption.
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