Australia's home price boom shows little sign of slowing, with Sydney and Melbourne again driving price gains after a brief lull in late autumn.

The widely-watched RP Data-Rismark Home Value Index shows prices jumped 3.7 per cent in Melbourne last month, with a 2.8 per cent rise in Darwin and strong gains also for Sydney and Canberra.

The more stable quarterly figures show Canberra defying public service austerity to post a 2.1 per cent increase in prices, while Sydney recorded a 2 per cent rise and Melbourne 1.8 per cent.

The heat in Australia's largest housing market is illustrated by Sydney's median dwelling price of $650,000 sitting more than $100,000 above the next dearest capital, Melbourne.

The gap between Australia's two biggest markets and the rest of the country widened further in the three months to July 31, with Sydney (14.8 per cent) and Melbourne (11 per cent) the only two markets posting double-digit annual gains.

All other markets were somewhat higher over the past year, with Brisbane's 6.9 per cent gain the best of the rest, but many cities saw prices go backwards in the past three months: Brisbane eased 0.4 per cent; Perth 0.1 per cent; Hobart 1.2 per cent; and Adelaide dropped 2.6 per cent.

Adelaide was recently found to be the only city where homes were selling around fair value if interest rates were to rise back to more typical levels.

Home price gains losing momentum: RP Data

However, RP Data's research director Tim Lawless says the past six months have shown a slower pace of price appreciation than the peak of the boom in winter and spring last year, and he expects this moderation to continue.

Home prices in July Sydney: up 1.5 per cent, median price $650,000.

up 1.5 per cent, median price $650,000. Melbourne: up 3.7 per cent, median price $540,000.

up 3.7 per cent, median price $540,000. Brisbane: down 0.1 per cent, median price $450,000.

down 0.1 per cent, median price $450,000. Adelaide: down 0.1 per cent, median price $395,000.

down 0.1 per cent, median price $395,000. Perth: down 0.5 per cent, median price $519,000.

down 0.5 per cent, median price $519,000. Hobart: down 0.6 per cent, median price $300,000.

down 0.6 per cent, median price $300,000. Canberra: up 1.5 per cent, median price $516,250.

up 1.5 per cent, median price $516,250. Darwin: up 2.8 per cent, median price $515,000.

"With interest rates remaining low and fixed rates seeing further downwards pressure, we are expecting that capital gains will continue into the foreseeable future," said.

"What is likely though is that the rate of capital gain will continue to reduce, particularly in those cities where affordability constraints are the most significant and rental yields are the lowest."

Mr Lawless has repeated a recent warning from Reserve Bank governor Glenn Stevens that the Sydney market looks most likely to ease off.

"Low yielding market conditions in Sydney and Melbourne are likely to act as a disincentive to investors, as well as the fact that these markets are well advanced in their growth cycle," he forecast.

"Additionally, with affordability becoming a more pressing issue in Sydney we would expect buyers to be seeking out medium to high density dwellings located close to the city rather than where they could afford to buy a detached home."

Outside the capitals, rest of state house prices fell 0.7 per cent in the three months to June 30, and were up a more modest 3.5 per cent over the last financial year.