Next Tuesday's budget will include an updated set of economic forecasts for the next four years, including growth, employment and wages.

"We are living in the most uncertain times any of us have seen in trying to get an understanding of what these numbers will be," the prime minister told the National Press Club in Canberra on Thursday.

"In that environment, I think Treasury's task, and the Reserve Bank's task - the OECD and others - their task is very, very difficult."

He said the government can do everything it can to boost the economy through the measures to be announced in the budget, but it is also vulnerable to what happens in the global economy.

A spread of economic figures released on Thursday highlighted the volatility that has been running through the economy during the pandemic, and shows what impact Victoria's harsh COVID-19 lockdown has had.

Job vacancies - a pointer to future employment growth - soared by a record 59.4 per cent in the three months to August, according to the Australian Bureau of Statistics.

In the May quarter, job vacancies had collapsed by 43 per cent, the largest fall in the 40 years of the survey. It overtook the previous record fall of 27 per cent during the 1990s recession.

"The large bounce in job vacancies is an encouraging sign that a recovery in labour demand is occurring," National Australia Bank economist Tapas Strickland said.

Meanwhile, Melbourne's tough COVID-19 restrictions may be easing but the state capital's housing market remains under pressure.

New figures show Melbourne house prices fell by a further 0.9 per cent in September and are now 5.5 per cent below a peak recorded in March. Prices are up just 3.1 per cent on the year.

This, and a soft Sydney market, dragged the national value of housing down for a fifth straight month.

Nationally, house prices were down 0.1 per cent in September to be 4.8 per cent up on the year, the CoreLogic hedonic home value index showed.

Still, the national fall in prices was the smallest decline since values started to reduce in May this year.

Even Sydney, where prices fell 0.3 per cent in the month, the rate of decline has been consistently easing. Sydney prices are up 7.7 per cent on the year, the strongest annual rise among Australian capitals.

"Prices have held up much better than feared back in March," AMP Capital chief economist Shane Oliver said.

"But that's mainly because JobKeeper, the increase in JobSeeker, the bank payment holiday and other support measures protecting heavily indebted households and property investors have headed off distressed sales."

Victoria's virus restrictions also continued to weigh on Australia's manufacturing sector, which suffered slower orders and inquiries nationwide.

The Australian Industry Group performance of manufacturing index fell 2.6 points to 46.7 in September, indicating a faster pace of decline than in August.

Index results below 50 points indicate the sector is in contraction.

The prime minister used his press club speech to outline a $1.5 billion budget boost for manufacturing, targeting mining, food and drink, medical products, recycling and clean energy, defence and space.

Australian Associated Press