The twin storms, dubbed the "cyclone sandwich" by locals, struck within hours of each other, about 2,500 kilometers apart.
Cyclone Lam hit a sparsely populated stretch of the Northern Territory, while the more powerful and potentially dangerous Cyclone Marcia crossed over small towns along the east coast of Queensland state, packing wind gusts up to 285 kilometers an hour.
Despite the storms' ferocious winds and drenching rains, no injuries had been reported by this afternoon, and both systems were steadily weakening as they moved over land.
"We are very, very thankful that we have avoided the worst of what could have been an absolute catastrophe," Queensland Premier Annastacia Palaszczuk said.
Marcia was originally predicted to be a relatively weak cyclone, but grew in strength at an alarming rate late on Thursday  into a menacing Category 5 storm, the most powerful form of cyclone in Australia.
The storm's rapid growth prompted Queensland Police Commissioner Ian Stewart to warn: "This is going to be a calamity, there's absolutely no doubt about that."
About 30,000 people living in and around the Queensland town of Yeppoon, 700 kilometers north of the state capital, Brisbane, were initially expected to experience the worst of the storm, and nearly 900 residents in low-lying areas were told to evacuate.
But a slight change in the cyclone's path spared the town the most ferocious winds, and it steadily weakened as it headed south toward the city of Rockhampton, home to about 80,000 people.
Yeppoon resident John McGrath, who rode out the storm with his family in their house just 100 meters (330 feet) from the beach, watched as the roof of his neighbor's home peeled off, flew through the air and landed across the road.

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