Tropical Cyclone Marcus is strengthening as it heads towards Darwin, and residents of the city have been told to brace for winds of more than 130km/h.
The cyclone intensified to a category two storm around 6.30am on Saturday as it bore down on the Northern Territory capital.
It was about 95 kilometres northeast of Darwin and moving southeast by around 12 kilometres an hour, the Bureau of Meteorology said.
A warning zone is currently in place from Wadeye to Croker Island, including Darwin and the Tiwi Islands.
The BOM told Darwin residents to expect wind gusts of more than 130km/h over the next few hours.
Authorities have also warned heavy rain and tidal surges could bring flooding to some areas.
Emergency services have told residents to stay inside until the storm passes, and those concerned about the safety of their homes should consider moving into one of the cyclone shelters opened around the city.
'If you're worried about your home being flooded or unsafe, those shelters are open today, but you need to head there now,' Regional Controller Warren Jackson said.
Mr Jackson also urged businesses to close their doors.
'Government businesses are closed today. We're asking other businesses to consider the same measures,'
'Employers should think about their duty of care to their staff when they consider whether to open today.'
Marcus is expected to weaken later on Saturday as it passes along the coastline, but is forecast to strengthen on Sunday as it move towards the northern Kimberly.
As Marcus approached on Friday, the AFL Northern Territory moved its grand final series in Darwin from Saturday to Sunday.
'A final call will be made, no later than 8am Sunday should the warning remain in place or the stadium be deemed unsafe or unfit to play on,' the competition said in a statement.
The Palmerston Council election scheduled for Saturday has also been postponed to next weekend.