Millions of people along Australia’s most densely populated coast braced for life-threatening flooding and days without power as Cyclone Alfred dumped a rain bomb on saturated catchments and powerful winds knocked down trees and electricity lines.

Winds cut electricity to nearly 100,000 homes and businesses on Friday night as the impact of the most powerful storm to threaten the coast so far south in 50 years began to be felt across a zone stretching from near Gympie in Queensland to Ballina in NSW well before landfall, which was due about midday on Saturday.