"I certainly wouldn't want to see us have another year at this level, otherwise we will be putting ourselves under significant risk that we are in a real bubble," Loan Market mortgage adviser Bruce Patten said.
The figures were released exclusively to the Weekend Herald by Auckland's biggest real estate firm, Barfoot & Thompson, which controls about a third of the local market. They measure the jump in median sale prices for the six months between February and July 2015 compared with the same period last year.
Milford topped the list, recording a dramatic 46.3 per cent increase - almost twice the Auckland average - to $1.161 million.
Herne Bay, Auckland's only $2 million suburb, failed to make the list. But outlying suburbs Te Atatu Peninsula, Te Atatu South, Manurewa, Papatoetoe and Glen Eden have all stormed into the top 20 as price-conscious buyers target more affordable areas.
Barfoot director Peter Thompson said the list showed a diverse city, with different types of suburbs and price brackets enjoying price growth above and beyond the norm.
The list highlighted the continued popularity of the North Shore, particularly areas close to beaches, good schools and transport links, he said.
But up-and-coming suburbs such as Sandringham, Sunnynook and Te Atatu Peninsula were now cementing their positions as more Aucklanders discovered their unique offerings.
"These locations, while all quite different, share some key characteristics. They sit on the city's edge or just beyond with good access to main transport routes, are home to flourishing 'village' centres and have been well positioned for growth as some of the more affordable suburbs in Auckland." Mr Thompson put easing house prices recently down to traditional winter market factors.
But he added that some vendors "are now trying to get more than what their home is worth and purchasers are saying 'enough is enough'.
"So a warning to vendors: Don't overprice your property. People won't just keep paying high dollar, prices have levelled off."
Mr Patten echoed those sentiments. "People are getting a bit too greedy and buyers are ... prepared to walk away.
"If people do want to sell they'll have to be in the market realistically and not looking to make that extra two or three hundred grand that some of them have over the last two to three months."
Mr Patten suggests home buyers should wait six months before fixing the interest rate on their loan.
His advice comes as all the major banks continue to trim their floating and fixed rates.
Mr Patten, of advisory firm Loan Market, said: "If you're were about to take out a mortgage, I would fix for six months because fixed rates are around 4.6 per cent whereas floating is still in the high 5s. So there's no point paying a premium on floating.
"If I was renewing a mortgage, I'd do the same: Six months fixed, not floating," he said.
"It's a big call, when interest rates might go up again. We won't see any changes until 2016 or 2017, the way the world economy is at the moment.
"Inflation won't go up and there's no reason to raise interest rates if we're in a low or zero-inflation environment.
"I think we're entering a period that's not like anything we've seen in the past three decades, where inflation has run at very, very high levels. Inflation won't kick back in in New Zealand for a good 12 months," Mr Patten predicted.
Kiwibank yesterday cut its rates, a day after the Reserve Bank shaved the official cash rate and signalled that more reductions were to come.
State-owned Kiwibank cut its floating or variable rate to 5.9 per cent. It is now offering six-month rates at 5.19 per cent and its cheapest rate is 4.59 per cent for a two-year term.
Other major banks have all moved to cut rates.
Additional reporting Anne Gibson
