Sale prices for Auckland houses jumped $16,000 last month and agency Barfoot & Thompson said the average hit $547,883, the highest for six months.
But one economist said the extremely low number of sales indicated a market without much fizz and the Rugby World Cup could be suppressing sales.
Barfoot managing director Peter Thompson said spring had arrived early, but Philip Borkin of Goldman Sachs said the market was lacklustre.
"Perhaps the Rugby World Cup, which is an Auckland-centric event, is resulting in normal activity being delayed," Mr Borkin said.
Mr Thompson was upbeat about the figures, which showed 738 sales in August, down on July's 758.
"The September average sale price was up more than $16,000 or 3.2 per cent on August and up $24,000 or 4.9 per cent ahead of that for the same month last year.
"This is a significant price increase given that for the past four months the average price moved no more than $2000 from $529,000 to $531,000.
"Traditionally prices rise at the start of spring, and in anticipation that the hype around rugby might interfere with our normal spring promotions, we brought our marketing campaigns forward by a month.
Certainly as a result of that, a number of sellers actively sought to list earlier than they might have otherwise done."
Six houses were sold for more than $2 million and a further 45 for $1 million-plus.
"The number of homes sold in excess of $1 million was 17 per cent of all our sales by value for the month, which is a far greater proportion of sales than normal," Mr Thompson said.
"We continue to sell more homes on a monthly basis than we did last year, but sales numbers have remained in a tight band between 778 and 738 for the last three months.
New listings at 1263 were up 5 per cent for the same month last year, and for the second month in a row new listings exceeded 1200.
"New listings remain tight and at the end of the month we had only 4798 homes on our books, 36 more homes than last month's number, which was our lowest on record for four years," Mr Thompson said.
Buyers have complained about a shortage of homes for sale, and desirable properties in suburbs such as Epsom are selling for well over their valuations.
Mr Borkin said Barfoot's sales numbers were down 9 per cent from August to September.
That was the third consecutive monthly fall after drops of 3.2 per cent in July and 4 per cent in August.
The average sale price had been boosted by an increased proportion of higher-valued property sales.
September Real Estate Institute data is not available but Reserve Bank figures show the number of mortgage approvals has continued to rise.
Property this year
Source: Barfoot & Thompson average Auckland house price.