'Once in a century' floods hit northeast Australia

Once in a century floods have turned streets into rivers and forced thousands to abandon their homes in northeast Australia, with authorities warning of further downpours over the next few days.

Australia's tropical north experiences heavy rains during the monsoon season at this time of the year, but the recent deluge has surged far above normal levels.

Thousands of residents in the city of Townsville in northeast Queensland were without power and up to 20,000 homes are at risk of being inundated if the rains continue.

Military personnel were delivering tens of thousands of sandbags to affected locals, as Queensland Premier Annastacia Palaszczuk warned residents to be careful.

"It's basically not just a one in 20-year event, it's a one in 100-year event," she told reporters Saturday.

The Bureau of Meteorology said a slow-moving monsoonal trough was sitting above northern Queensland state, with some areas expected to receive more than a year's worth of rain before conditions ease.

"We could see the rain intensify into early next week as the low... moves out to the Coral Sea," meteorologist Jonathan How told national broadcaster ABC Sunday.

The region receives an average of some 2,000 millimetres (6.5 feet) of rain annually but some towns were already on track to pass that total.

The town of Ingham received 506 millimetres of rain in 24 hours between Saturday and Sunday, of which 145 millimetres fell in just one hour, he added.

I've never seen anything like this," Townsville resident Chris Brookehouse told the ABC, adding that more than one metre of water had flooded his house.

"The volume of water is just incredible. Downstairs is gone, the fridge and freezer are floating. Another five or six steps and upstairs is gone too."