Police in the Northern Territory say more than 100 people have been evacuated from low-lying properties in the path of Tropical Cyclone Monica.
The very destructive core of the severe tropical cyclone, with gusts to 290 kilometres per hour, may approach the north-east Arnhem Land coast early on Sunday.
Gales may extend further west into Arnhem Land and along the coast to Point Stuart, including Cobourg Peninsula later on Sunday.
Dangerously high tides could cause extensive flooding at the coast between Groote Eylandt and Elcho Island tonight and on Sunday.
Heavy rain is expected to cause significant stream rises and flooding of low lying areas on Sunday in north-eastern Arnhem Land.