Officials and locals said 90 per cent of the main street in the small Queensland town of Tully, south of Cairns, had "extensive damage", while the coastal community of Cardwell also suffered "significant devastation".
"There are people now that have lost their homes, they lost their farms, they have lost their crops and they have lost their livelihoods and I have no doubt that many of them will experience a great sense of despair," Queensland state premier Anna Bligh said.
But regional hub Cairns, a centre for foreign tourists visiting the Great Barrier Reef, was spared Yasi's worst with problems largely restricted to fallen trees and minor damage to buildings.
No deaths or serious injuries were immediately reported, due to what officials said was good planning, strong public warnings and the fact that the storm veered suddenly southwards, away from Cairns, home to 122,000 people.
"This was the worst cyclone this country has experienced, potentially, for 100 years and I think that due to very good planning, a very good response [...] we've been able to keep people safe," state emergency services minister Neil Roberts said.
Power blackouts darkened 177,000 homes across the region and major roads were closed by flooding or storm debris.
Authorities are warning residents to stay in their homes to avoid a second storm surge along the coast and fallen power lines.
"People cannot let their guard down yet. The danger is not over," Australia's Prime
Minister Julia Gillard said.
Queensland, a mining, farming and tourism hotspot, is still battling to recover from floods which left about three-quarters of the state under water, even inundating large parts of its capital, Brisbane.