Australia's core inflation rose faster than expected in the September quarter, with the Reserve Bank of Australia's preferred quarterly trimmed mean gauge climbing to 3.7% from a year earlier, data from the Australian Bureau of Statistics showed Wednesday. Headline consumer prices rose 4.3% in the 12 months to September, up from 4.0% in August.

The figures strengthen the case for a fifth quarter-point increase this year when the RBA's board decides on Nov. 3. A move would lift the cash rate to 4.85% from 4.60% and widen Australia's yield premium over Japan, South Korea and China, a gap that matters to investors in Hong Kong, Singapore and Jakarta who hold Australian bonds or trade the Australian dollar against lower-yielding Asian currencies.

Core Inflation Runs Ahead of the RBA

The trimmed mean, which strips out the largest price rises and falls, rose 1.0% in the quarter, up from 0.8% in the June quarter. That matched economists' forecasts but beat the 0.8% the RBA had projected in August, AAP reported.

The annual rate edged up from 3.6%. Economists had expected it to hold there, according to a Bloomberg survey cited by The Conversation. The quarterly trimmed mean now appears in an appendix to the bureau's monthly release, compiled on pre-October 2025 methods. The bureau's main trimmed mean, now calculated monthly, was 3.6% in the year to September, up from a revised 3.5% in August.

Headline prices rose 1.3% in the quarter, more than double the June quarter's 0.6% and above the 1.2% forecast cited by investingLive. In September alone, the index rose 0.8%, or 0.6% after seasonal adjustment.

Fuel did most of the damage. Automotive fuel rose 9.4% in September on higher world oil prices, the ABS said, after a 14.8% jump in August, leaving it 23.6% more expensive than a year earlier. Because fuel is excluded from the trimmed mean, it explains much of the gap between headline and underlying inflation, the bureau said.

Housing remained the largest contributor, rising 5.2% over the year, down from 5.7% in August. Electricity was 12.8% dearer, largely because Commonwealth rebates on household power bills ended, while new dwelling prices rose 4.7% and rents 3.6%. Domestic holiday travel and accommodation jumped 8.0% in the month on school holidays and major sporting events.

Price pressure also showed up beyond energy. Services prices were up 4.1% from a year earlier, and market services inflation, which covers items such as insurance and hairdressing, rose above 4% for the first time since late 2025, Deloitte Access Economics partner Stephen Smith said, according to AAP.

Markets Bet on a Melbourne Cup Day Hike

RBA Governor Michele Bullock told a Senate committee shortly before the release that inflation would likely run above the bank's August base case. She cited a renewed surge in global energy prices tied to conflict in the Middle East and said the labor market looked a little tighter than previously judged, even though unemployment had risen slightly more than expected. A key question for the board, she said, is whether the 100 basis points of tightening delivered this year is enough, adding that the bank “can’t allow high inflation to persist.”

Bond market pricing for a November increase rose above 80% after the data from about 60% beforehand, said Marc Jocum, senior investment strategist at ETF provider Global X, who called the result “an ugly number for the RBA,” AAP reported. National Australia Bank and Commonwealth Bank of Australia, which had both expected a hold, now forecast a hike, joining ANZ and Westpac. NAB chief economist Sally Auld said the central bank may need unemployment to reach 5.5% rather than 5%, AAP reported.

Not everyone sees the decision as settled. Monash University economist Isaac Gross wrote in The Conversation that the fuel-driven jump should be weighed against a more modest monthly core reading, weaker consumption and rising unemployment, and that a hold would give earlier increases time to work.

The Australian dollar found little lift. It traded around 70.30 U.S. cents on Wednesday, pressing against technical resistance where its 100-day and 200-day moving averages converge, investingLive analyst Justin Low wrote.

Australia Joins Asia's Tightening Wave

Bullock told senators that central banks in many advanced economies are raising rates or signaling they will if needed. Capital Times has tracked Asia's swing toward tighter policy this year as energy costs lift prices.

At 4.60%, Australia's cash rate sits well above Japan's 1.25% and the 3% benchmark rates in South Korea and China, though below India's 5.5% and Indonesia's 5.75%, according to Trading Economics. Another increase would add to the appeal of borrowing in low-yielding currencies such as the yen to buy Australian assets, a trade that pays only as long as the Australian dollar holds its value.

New Zealand went the other way the same day. The Reserve Bank of New Zealand held its official cash rate at 2.75% in a 4-3 vote, when markets had priced about a 90% chance of a hike, investingLive reported. The site said the widening gap in rate expectations generally favors the Australian dollar against its New Zealand counterpart.

Part of Australia's inflation is also arriving from the AI boom. Bullock said the global boom is lifting growth in economies that are key parts of the AI supply chain and pushing up prices for supply-constrained technology. The ABS data show it at the checkout: prices for games, toys and hobbies rose 15.5% over the year, which the bureau attributed to costlier memory and storage components, the market where SK Hynix just posted a record profit.

The RBA's decision on Nov. 3 will come with new forecasts showing how far it has raised its inflation outlook since August.