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After a softness in the last half of last year, retail spending rebounded 1.5% in the three months ended March, Statistics NZ figures showed.
Westpac senior economist Satish Ranchhod said most of the increase was the result of a large 5.9% increase in motor vehicle sales.
There were gains in most categories and core spending was up 1.2% in the quarter.
There was also a strong lift in spending on food services such as dining out, along with continued gains in spending on accommodation. Both of those factors were consistent with the strong tourist season, he said.
Spending on durable items like electronics and furnishings also increased.
''After signs spending was losing momentum in the latter half of 2016, this is a positive result pointing to some continued momentum in activity. However, we have some doubts this strength will be sustained over the remainder of the year.''
One of the big drivers of spending on household items in recent years had been low interest rates and the related strength of house prices, Mr Ranchhod said.
In recent months, interest rates had risen and house price growth had pulled back.
Westpac expected more moderate household spending growth in coming months, offsetting some of the boost to spending from continued strong population growth and tourist inflows.
Mr Ranchhod estimated overall prices were up nearly 2% in the past year.
Much of the recent increase in prices had been due to food and fuel costs. Prices for other goods continued to be subdued, he said.
The retail sales data started a busy week for New Zealand.
Results from the latest GlobalDairyTrade auction will be released tomorrow morning.
The index had increased in the past four auctions, for a total gain of 10.5% in the period.
Craigs Investment Partners broker Chris Timms said the GDT index was now only 2.5% below its December high, having been nearly 12% below those levels earlier this year.
Prices were 61% ahead of a year ago and the Fonterra payout - to be finalised in coming weeks - looked safe at $6, with a possibility of a small upgrade looking likely.
In terms of the opening payout for the new season, the $6 to $6.25 range seemed likely and the stability would be welcomed by the sector after the volatility of the past seasons, he said.
Migration figures were due at 10.45am on Friday.
Net migration hit an annual high last month, rising to 71,900 for the year ended March and surpassing the previous annual record from a month earlier, Mr Timms said.
The monthly net migration figure was 6100, up from February but not as strong as the record monthly gain in the first month of the year.
Annual net migration had been steadily increasing since 2012 and nearly three-quarters of all arrivals during the past five years had been citizens of other countries.
PushPay, Goodman Property, Infratil and Ryman Healthcare will report this week. In Australia, James Hardie will report its 2017 result.