Rescue crews were Wednesday searching for survivors after seven people died in heavy storms across Australia's eastern seaboard, including a 40-year-old woman sucked into a stormwater drain.

Thunderstorms and destructive winds have in recent days pounded the Australian states of Victoria and Queensland -- capsizing boats, sparking flash floods, and tearing down concrete powerlines.

The government weather bureau has warned that coastal regions in Queensland were still at risk of "dangerous" storms, "life-threatening" floods, "giant" hail, and "damaging" winds.

Three women were swept into a stormwater drain when floodwaters surged through the rural town of Gympie on Tuesday, some 180 kilometres (111 miles) north of Queensland's state capital Brisbane.

One of the women survived, a 40-year-old woman died, and emergency services now hold "grave concerns" for a 46-year-old who has not been found.

Queensland Fire and Emergency Services deputy commissioner Kevin Walsh said swift-water rescue teams would continue scouring the area on Wednesday.

Eleven people were tossed into the ocean when a boat capsized at sea near Brisbane. Police said Wednesday that two people had drowned, eight survivors had been scooped from the water and rushed to hospital, and they were still searching for a missing crew member.

"It has been a very tragic 24 hours due to the weather," police commissioner Katarina Carroll told reporters.

The body of a nine-year-old girl was found after she went missing in flood waters on Brisbane's outskirts, police said, while a 59-year-old woman was killed by a falling tree on Queensland's Gold Coast.

Utility company Energex said it was racing to restore electricity to more than 80,000 homes in the state.

"How strong were those storms? Enough to snap multiple concrete poles supporting high-voltage lines," it posted on social media.

Meanwhile in Victoria, a woman was found dead late on Tuesday evening after flash floods swamped a regional campground in Buchan, 350 kilometres (217 miles) east of the state capital Melbourne.

A man was killed after he was struck by a falling tree branch in Caringal, 180 kilometres (111 miles) east of Melbourne.