Twin severe tropical cyclones will hammer northern Australia over the weekend, smashing ecosystems and potentially leaving a hefty repair bill from damaging winds, storm surges and flooding.

Both Cyclone Trevor in the Gulf of Carpentaria and Cyclone Veronica off north-western Western Australia are likely to generate wind gusts reaching 275km/h as they near the coast, said Dean Sgarbossa, a senior meteorologist with the Bureau of Meteorology's extreme weather desk.

Cyclone Veronica, off the Pilbara coast, and Cyclone Trevor in the Gulf of Carpentaria are likely to batter large areas of northern Australia over the weekend. Credit:Himawari-8 Satellite

The trigger for the dual storms was a recent eastward pulse of cloud and rainfall along the equator, known as a Madden-Julian Oscillation. That helped shift southwards the monsoonal trough, which had been lying to Australia's north and producing a relatively dry wet season.

The right meteorological conditions combined with warmer than average waters, providing the energy needed for the cyclones to intensify rapidly, Mr Sgarbossa said. Waters in the Gulf are about 1 degree warmer than average, while those off the Pilbara are about 0.5-1 degree warmer than normal.