The Monthly CPI Indicator came in much stronger than expected, lifting to 2.8% year-on-year from 1.9%, well above the 2.3% consensus.
Underlying inflation also showed momentum, with the Trimmed Mean rising to 2.7% after readings of 2.1% in June and 2.4% in May.
Much of the upside was linked to the timing of electricity rebates and swings in travel-related prices.
Policymakers have previously cautioned that the first month of a new quarter can be volatile and less reliable, with greater weight placed on the full quarterly CPI update.
Markets adjusted only slightly, with September pricing easing back to around 5bp of cuts from 7bp, while expectations for November remain unchanged with a full 25bp reduction still implied.