Australia Core CPI Hits 3.7%, RBA November Hike Firms

Australia's trimmed mean CPI rose 1.0% in the September quarter and 3.7% year on year, the Australian Bureau of Statistics data released on 28 October 2026 showed, with the annual core rate landing above the 3.6% consensus and above the June quarter's 3.6%. Headline CPI rose 1.3% quarter on quarter against a 1.2% forecast, more than double the prior 0.6%. The release landed minutes after RBA Governor Michele Bullock told a Senate committee that inflation will likely exceed the central bank's August forecasts.

Context — why the RBA hike case just hardened

The report's own comparison is the one that matters. The RBA had expected core inflation to stabilise, and instead the annual trimmed mean climbed. That gap between forecast and outcome is the whole story, because the RBA still treats the quarterly trimmed mean as its primary gauge of underlying price pressure.

The prior quarter is the second reference point. Trimmed mean inflation ran at 0.8% quarter on quarter in the three months to June and 3.6% year on year. September's 1.0% quarterly print and 3.7% annual rate mark an acceleration on both measures, not the plateau the central bank had pencilled in.

The catalyst chain runs through energy. Bullock said the re-escalating Middle East conflict has pushed energy prices well above the assumptions behind the August forecasts, and she tied that directly to a worse inflation outlook. Headline CPI captures that pass-through first, which is why the quarterly headline print overshot by a tenth of a percentage point and the monthly series jumped.

Macro backdrop matters here too. The RBA has already delivered 100 basis points of tightening this year, according to Bullock's remarks, and she framed the central question for next week as whether that cumulative tightening will be enough to return inflation to target in a reasonable timeframe. Today's core reading argues it has not been enough yet.

Timing compounds the signal. Bullock's opening statement was delivered shortly before the data crossed, so the market received a governor saying inflation is running hot and then, within minutes, a core print confirming it. The Board meets on 2 and 3 November.

Data — what the numbers show

The quarter's inflation picture splits into a firm core and a marginally softer alternative measure.

Measure	Actual	Forecast	Prior
Q3 trimmed mean q/q	1.0%	1.0%	0.8%
Q3 trimmed mean y/y	3.7%	3.6%	3.6%
Q3 headline CPI q/q	1.3%	1.2%	0.6%
September CPI m/m	0.8%	0.7%	—
September CPI y/y	4.3%	4.2%	4.0%
September trimmed mean m/m	0.3%	0.3%	—
September trimmed mean y/y	3.6%	3.6%	—
Q3 weighted median q/q	1.0%	1.1%	—
Q3 weighted median y/y	3.6%	—	—

Before and after: annual headline inflation moved from 4.0% in the prior monthly reading to 4.3%, a three-tenths acceleration, while the annual trimmed mean moved from 3.6% to 3.7%.

The monthly data is the partial counterweight. The monthly trimmed mean rose 0.3% month on month and held at 3.6% year on year, both exactly in line with forecasts. The quarterly weighted median, a second underlying gauge, rose 1.0% against a 1.1% forecast and 3.6% year on year — a tenth softer than expected on the quarterly measure.

That split is the detail desks will parse. The RBA's preferred quarterly trimmed mean accelerated past forecast, while the monthly trimmed mean and the weighted median did not surprise to the upside. The quarterly pace also ran ahead of the roughly 0.8% implied by the RBA's August forecasts, which is the cleanest read on how far the central bank's own projections have been overtaken.

Analysis — what it means for rates, the Aussie and AUD/NZD

The immediate read-through is pricing for a hike at the 2-3 November meeting. A core measure that rises when the central bank expected it to hold supports that repricing, and it backs the Australian dollar and front-end yields, since a hawkish RBA compresses the gap between where cash rate futures sit and where the Board may actually move.

The weighted median is the honest counter-argument. A 1.0% quarterly print against a 1.1% forecast says the breadth of price pressure is a touch narrower than the trimmed mean alone implies, and a single softer alternative gauge is exactly the kind of detail a dovish Board member would cite to argue the existing 100 basis points is doing its work.

The sector exposure runs through energy first. Bullock's link between the Middle East conflict and higher energy costs means fuel and related input costs are the transmission channel into headline inflation, and any further rise in crude adds to the tightening case rather than subtracting from it. Domestic capacity pressure is the second channel, which is what the firmer core reading captures beyond fuel.

Positioning follows the rate path. Traders leaning into a November hike are effectively long the front end of the Australian curve and long the Aussie against lower-yielding counterparts, and today's data gives that flow a fresh justification rather than a reason to fade.

Outlook — what to watch next

The first catalyst is the RBA decision itself on 2 and 3 November, where the Board will publish updated forecasts alongside its call. Those revisions will show how far the inflation outlook has been marked up since August and whether the RBA judges further tightening necessary.

The second is the RBNZ decision at 01:00 GMT, which AUD/NZD traders face directly. A widely expected hike there could limit any relative move in the Aussie, because a hawkish RBNZ offsets an RBA-driven bid in the cross.

The third is energy. Crude is the variable Bullock named, so further escalation in the Middle East conflict keeps upward pressure on headline inflation and keeps the hike case alive between now and the November meeting. Watch the updated RBA forecasts for the size of the revision.

Frequently Asked Questions

What does the trimmed mean CPI measure and why does the RBA prefer it?

The trimmed mean strips out the largest price rises and falls in the quarter to show the underlying trend, which is why the RBA uses the quarterly version as its main gauge of core inflation. September's reading matters because the annual rate rose to 3.7% instead of stabilising as the central bank had forecast, suggesting price pressures are broadening beyond fuel into domestic capacity.

Why did Australia's headline inflation jump to 4.3% in September?

Bullock tied the deterioration to energy. The re-escalating Middle East conflict pushed energy prices well above the assumptions behind the RBA's August forecasts, and higher energy costs lift headline inflation directly. September headline CPI rose 0.8% month on month against a 0.7% forecast, taking the annual rate to 4.3% from 4.0% and above the 4.2% expected.

How does the RBNZ decision affect AUD/NZD traders on the same day?

The RBNZ decision lands at 01:00 GMT, and a widely expected hike there could limit any relative move in the Aussie even if the RBA hike case firms. A hawkish RBNZ supports the New Zealand dollar against its Australian counterpart, offsetting part of the AUD/NZD bid that stronger Australian core inflation would otherwise generate.

Bottom Line

A core inflation rate that rose instead of stabilising locks in the case for an RBA hike on 2-3 November.

Disclaimer: This article is for informational purposes only and does not constitute investment advice. CFD trading carries high risk of capital loss.