The Reserve Bank is mandated with keeping annual inflation between 1-and-3 per cent over the medium term with a focus on the mid-point.
However, inflation has remained stubbornly weak, only pushing up to a 2.2 per cent annual pace briefly in the March quarter before dipping back to 1.7 per cent in the June quarter and 1.9 per cent in the September quarter.
Acting Reserve Bank governor Grant Spencer kept the official cash rate at 1.75 per cent as widely expected at the November review and the central bank's forecasts show it does not expect to lift rates until mid-2019 at the earliest.
Bank of New Zealand senior economist Craig Ebert said the data "was clearly a surprise to the south" and will keep the Reserve Bank on hold. He said given the central bank was "not on the front foot in talking about normalising policy in November, data like this are hardly going to encourage it to change its tune."
ASB Bank senior economist Jane Turner also said the data reinforces the view that the central bank will remain on the sidelines. "This release suggests that inflation has yet to stage a convincing comeback in NZ, outside of the housing sector. And, with this release raising numerous questions about the strength of inflation moving forward, it reinforces that there is no need for the RBNZ to raise interest rates anytime soon," she said.
Inflation was lower than expected as higher fuel prices were offset by a slide in food prices and as some major retailers move away from short-term discounts and specials to consistently lower prices for retail goods.
The tradables CPI, which includes goods and services that compete with international rivals, fell 0.3 per cent in the quarter and was up 0.5 per cent on the year. Non-tradables inflation, which focuses on domestic goods and services, rose a quarterly 0.5 per cent for a 2.5 per cent annual increase.
Economists said the downside surprise was largely in the tradable component, with the most significant declines in clothing, household contents and new car prices.
Westpac Banking Corp senior economist Michael Gordon said "it's likely that the gains in the New Zealand dollar earlier in 2017 are still flowing through into retail prices of imported products. However, the results also suggest a lack of price pressures in internationally-traded goods as a whole."
Overall, however, the data underscore that "New Zealand's inflation pulse remains soft" and markets were wrong to price an interest rate hike this year. "We don't expect any until the second half of 2019," said Paul Dales, chief Australia and New Zealand economist for Capital Economics.