Cyclone Monica has forced the cancellation of Darwin's Anzac Day dawn service and march.
The maximum strength, category five cyclone is about 550km east, north-east of Darwin and should reach Arnhem Land's west coast later today.
Monica, which has winds of up to 350kph at its core, is expected to reach Darwin and the Tiwi Islands by Tuesday.
The cyclone has prompted the Darwin RSL to announce that the Anzac Day dawn service will be cancelled along with the 10am (AEST) march through Darwin's main streets.
"We made the decision because we didn't want to damage some of the old war equipment we use in the march and obviously we need to protect the people as well," he said.
Mr Shaw said the decision was not made lightly.
"It's Australia's biggest day and we have to cancel it, so people are very upset," Mr Shaw said.
Cyclone Monica is moving in a north-westerly direction at 15kph and Darwin residents have been urged to secure their homes and stock up on essential supplies.
"We're hoping as it hits the land it will lose some intensity, but there's no doubt a serious cyclone is on the way," said the Bureau of Meteorology's Andrew Tupper.
"Strong wind gusts are expected at Darwin by tomorrow morning and the cyclone is not showing any signs of weakening."