SYDNEY—Australia’s inflation rate is expected to slow in the third quarter, but there is uncertainty about how long it will last, leaving the Reserve Bank of Australia reluctant to consider raising interest rates anytime soon.

Speaking at a luncheon with economists on Wednesday, RBA Deputy Governor, Guy Debelle, said he expects the forces cooling off inflation (mostly falling utility prices) to abate, but added that, “there is uncertainty about how much longer they will persist.”

“We would like to be more confident that inflation will be sustained at a rate consistent with the target,” he said.

Over the past three years, inflation has averaged 1.8%. The RBA targets a rate between 2-3% on average over the course of the economic cycle.

Mr. Debelle’s remarks are consistent with the RBA’s well established mantra that it sees no strong case to raise interest rates just yet. He added that gradual progress on lowering unemployment and bringing inflation closer to the midpoint of the target is expected over coming years.