SYDNEY (Reuters)—Australia faces an above-average number of cyclones over the coming storm season, meteorologists said Monday, threatening new devastation after massive floods swamped homes, as well as destroying crops and crippling mining earlier this year.

The northwest offshore oil and gas field and coastal iron ore operations face a 65% chance of being hit by more than seven cyclones, Australia's Bureau of Meteorology said in its 2011-12 tropical cyclone season forecast.

Northeast Australia, where coal mining was crippled last year due to heavy flooding partly generated by cyclones, also faces a 65% chance of more than the average of three to four cyclones this season, said BOM.

In total, Australia's north may be hit by more than 12 cyclones due to neutral to borderline La Niña weather conditions, which bring wet weather to the western Pacific, fueling tropical storms over the ocean.

"Historically, these conditions have favored an above-average number of cyclones in the Australian region," said the BOM.

Australia's cyclone season is between November and April.

Natural disasters including floods and cyclones cut economic activity by 0.75 percentage points in 2010-11, wiping $1.75 billion Australian ($1.81 billion) from revenue across 2010-11 and 2011-12, Treasurer Wayne Swan said.

Australia's third-largest city, Brisbane, was inundated with floodwaters, and flooding across an area as big as France and Germany forced major miners to declare force majeure and damaged large swaths of croplands, including the key sugar crop.

Australia, one of the world's largest coal exporters, accounts for about two-thirds of the global coking coal trade, with around 90% of that coming from Queensland state.

Coking or metallurgical coal is used for steelmaking, with the bulk of Australian exports to China.

Global miners Rio Tinto, BHP Billiton and Xstrata are among major companies involved in coal mining in Queensland.

One of the most powerful La Niñas in recent years fueled the devastating 2010-11 cyclones and floods, and the BOM said another, less powerful La Niña would likely develop in 2011-12.

"Before a tropical cyclone forms, it is difficult to predict its exact strength and path, including whether it will make landfall," said the bureau.

"Along the east and west coasts, fewer than half of the cyclones affect the coast, with most staying out to sea. Along the north coast, more than half of the cyclones impact the coast. Tropical cyclones which remain out to sea can still cause storm surges, gales and areas of intense rain over land."