Houses in regional New Zealand are becoming more expensive, as people flee the red-hot Auckland market.

Houses in Auckland are more affordable than they were in September, but are still 59 per cent less affordable than anywhere else in the country.

The latest report from Massey University, which covers October to December 2015, showed that despite continuing high values and severe unaffordability in Auckland, there had been a slight quarterly improvement of 1.4 per cent.

This reflects the overall affordability of housing in New Zealand, which increased 5.7 per cent.

"The margin by which Auckland exceeds the national figure continues to increase and at 59 per cent less affordable than the whole country, it tops historical levels," it said.

Housing affordability is assessed by comparing the average weekly earnings with the median dwelling price and the mortgage interest rate.

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Last month, Real Estate Institute New Zealand (REINZ) released figures showing the median sale price for 2015 in Auckland was $745,500.

Excluding New Zealand's biggest city, the national median price rose 4 per cent, to $355,000.

"Government imposed financial constraints including the loan to value ratio of 70 per cent in Auckland and 80 per cent elsewhere - together with the taxation implications for investment property - may have affected the Auckland market," Massey University's report said.

"Requirements to provide an IRD number and internal constraints in China on overseas investment may also have reduced demand amongst this cohort of investor buyers."

The Nelson, Marlborough and Kaikoura region and Central Otago Lakes regions were the "winners in the affordability race", it said.

House prices rose again in all regions except the Nelson, Marlborough and Kaikoura region, where gains reported in the September quarter were not sustained, it said.

The median house price in the Nelson, Marlborough and Kaikoura region has fallen by $10,000 to $375,000.

It is also cheaper to buy a house in Canterbury/Westland and the Hawke's Bay, who have improved affordability by 2.4 per cent and 1.8 per cent respectively.

Nationally, interest rates had continued to fall and despite words of caution from the Reserve Bank governor, there was some speculation that a historically low official cash rate of 2.5 per cent could fall even further, the report said.

"This may encourage more people, both homeowners and investors, into the market increasing demand and putting upward pressure on prices.

"Despite moderate value increases in other areas, interest rate drops and some wage increases mean improvements in affordability in this quarter are scattered across the nation."

In other major regions, housing affordability decreased, with Southland the most affordable region to buy a home.

Wellington affordability decreased 3.3 per cent and Manawatu/Whanganui dropped 2 per cent.

A decline in affordability was also seen in the Waikato/Bay of Plenty - arguably reflecting the 'Auckland Ripple Effect', it said.