Brisbane has been declared a natural disaster area, as soldiers and prisoners help repair damage caused by one of the biggest storms to hit the city in two decades.

About 30,000 properties across Brisbane, Redcliffe and the Gold Coast were without power on Monday afternoon after Sunday's storm brought hail and wind gusts of up to 130km/h, unroofed homes and toppled power lines and trees.

Emergency authorities said up to 4,000 homes were damaged, with 300 homes "significantly damaged" and 30 deemed unlivable.

While most areas received 40mm to 60mm of rain, Ferny Hills, in the north-western suburbs of Brisbane received 80mm, 69mm of which fell in the space of 30 minutes on Sunday afternoon.

A 20-year-old man was killed when he was swept away by quickly rising water while photographing the storm in a drain with a 23-year-old friend at Chermside, in Brisbane's northern suburbs.