The Tiwi Islands Football League grand final has been postponed as residents prepare for the predicted Tropical Cyclone Marcus, which could bring winds of up to 125 kilometres per hour.

Key points: A tropical low off the coast of Darwin is expected to intensify to a category one tropical cyclone tomorrow evening

A tropical low off the coast of Darwin is expected to intensify to a category one tropical cyclone tomorrow evening Residents from Milingimbi to Daly River Mouth, including Darwin and the Tiwi Islands, are on cyclone watch

Residents from Milingimbi to Daly River Mouth, including Darwin and the Tiwi Islands, are on cyclone watch Darwin could see up to 200mm of rain in 24 hours

Thousands of spectators were expected to attend the annual Tiwi Islands football match 80 kilometres off the coast of Darwin this Sunday, which will instead take place on Sunday, March 25.

The Bureau of Meteorology has warned a tropical low is 250 kilometres north of the Tiwi Islands, and is expected to form a category one tropical cyclone that will "brush past" Darwin Friday evening.

It was expected to move south-east across the Arafura Sea on Thursday before turning towards the north coast of the Top End during Friday.

Residents from Milingimbi to Daly River Mouth, including Darwin and the Tiwi Islands, are on cyclone watch.

A flood watch will also be issued for north-west coastal rivers.

The predicted path of a cyclone developing off the coast of Darwin and expected make landfall on Friday. ( Supplied: Bureau of Meteorology )

"The system is expected to brush past Darwin, and the impacts on Darwin are expected late Friday evening, with a wet and windy night forecast," the Bureau of Meteorology said.

"The most likely track is for the system to pass between the Tiwi Islands and the Coburg Peninsula tomorrow night before moving into the Van Dieman Gulf, offshore from Darwin."

The city could see heavy falls, with 24-hour rainfall totals of 100-150 millimetres, potentially up to 200mm.

Winds gusts are expected to be within 95 and 125kph.

However, the severe conditions in the city were expected to be brief .

There was also a chance the system would cross further to the east of the Coburg Peninsula, which would force the system to weaken over land before approaching Darwin.

If the cyclone did form it would be called Tropical Cyclone Marcus and would be the first in the Northern Territory for the 2017-2018 season.

Those within the cyclone watch area have been advised to prepare homes, yards and families for a cyclone, pull together an emergency kit and decide where to shelter.

Annual match postponed

The 2018 Tiwi Islands Football League grand final has been postponed until March 25. ( ABC: Felicity James )

Tiwi Islands Football League grand final manager Chris Smith said the focus would shift to preparing the community for the predicted cyclone.

"We know that when nature gets going we've just got to stand aside really," Mr Smith said.

"We have to abandon our preparations for the grand final and focus on the community and the local businesses here."

While he could not gauge what impact the delay would cause to the local economy, he hoped supporters would still come out on March 25.

"I'm hoping that people still want to come out here and enjoy a great game of football," he said.

Sealink business manager Angela Panagopoulos said those with ferry tickets to go to the Tiwi Islands this Sunday could use them the following Sunday, or a refund would be offered.

The free seats would be sold to people on their waiting list — which already had more than 200 people.

Fly Tiwi was rescheduling flights for the following weekend.

AFL Northern Territory chief operating officer Stuart Totham said the Northern Territory Football League would be going ahead with its grand final on Saturday as planned, at this stage.

"When we're under a cyclone watch generally our football will go ahead, as long as there's not lightning around, that sort of thing," Mr Totham said.

"If we go into a warning situation, clearly all bets are off.

"We'll just sit and watch this for the next 24 hours. See where we are this time tomorrow and go from there."