Australia’s housing slowdown is broadening, with property values falling across the vast majority of suburbs in the nation’s capital cities as weaker demand and higher borrowing costs continue to weigh on the market.

New data from property research firm Cotality shows national home values fell 0.9 per cent in August, marking the fifth consecutive monthly decline. The national median property value is now 3.6 per cent below its March record high.

Sydney remains at the centre of the downturn. Home values in the city dropped 1.4 per cent in August, leaving prices 7.1 per cent below their February peak. Melbourne and Canberra each recorded a 1.1 per cent decline, while Brisbane fell 1 per cent.

The downturn is no longer limited to Australia’s most expensive housing markets. Cotality estimates that 93 per cent of capital-city suburbs recorded falling values during winter, up sharply from 45.8 per cent in autumn.

Cotality research director Tim Lawless said the market had shifted from a more concentrated slowdown to a much broader decline, with falling demand and elevated property listings putting increasing pressure on prices.

Buyer activity also appears to be weakening. Real estate agency Ray White says the average number of people attending its open homes has fallen from around four last year to approximately two this year.

Economists warn that the housing market could face further pressure if interest rates rise again or unemployment increases significantly.

While Perth continues to record strong annualised growth of around 20 per cent, Sydney and Melbourne are moving in the opposite direction, with annual declines of roughly 7 to 8 per cent.

The latest figures come after three Reserve Bank interest rate increases and federal changes affecting negative gearing and capital gains tax, adding further uncertainty for investors and prospective buyers.

With Australian households carrying some of the highest debt burdens in the world, economists say a further deterioration in employment could make the housing downturn significantly more severe.