Superintendent Engels says the public shelters in Darwin are not open at this time, as they are not expected to be needed.

"We want you to stay home," she says.

"If you feel like … you cannot stay at your home, find somewhere safe to move to today. There's no need to panic, just be prepared."

Asked how people will know if the situation changes, she says there will be "very overt messaging" in the media letting people know that shelters have been opened.

While the government won't direct businesses in Darwin to close, buses won't be running tomorrow, Superintendent Engels says.

The MVR office on Goyder Rd will be closed, too.

"Don't go there," she adds.

Superintendent Engels says NT police expect to issue a similar call to Darwin residents to take shelter tomorrow, meaning today is the final day in which residents will be able to make preparations for Fina's arrival.

"Based on the information we have, we are comfortable that your homes are able to withstand the event," she says.

"If you have concerns, we ask you to go and find somewhere that you feel safe to shelter in.

"When the storm impacts are starting to be felt. We ask you to park your car, find your shelter and stay there until you are told it is clear to go out."

Superintendent Engels issues a similar call for residents of the Tiwi Islands to find shelter before darkness tonight.

She says the ferry between Darwin and the islands is no longer running.

Superintendent Engels says police are asking residents of Minjilang and Warruwi to "pick their place of shelter and to be there before darkness tonight".

She says there are about 280 people in the Minjilang community, and reminds them that an emergency shelter is open in the local school.

"I can tell you that Minjilang residents have been through this before. They're prepared, and they're ready," she says.

A shelter in Warruwi has also been open since last night, she adds, and residents of both communities have "plenty of food and water".

Next up is the NT Police Force, with Superintendent Kirsten Engels addressing the media.

She says police are preparing for all scenarios, and have set up an emergency hotline that will be available from this afternoon.

The number to call is 1800 888 901.

The bureau has issued a flood watch for much of the NT's north, Ms Gamble says, with daily rainfall totals of 200mm expected across the watch area.

Flash flooding is possible, particularly around coastal communities, while a storm tide of about one metre above the highest tide is expected around Minjilang.

Ms Gamble warns NT residents that thunderstorms with damaging and even destructive winds, as well as heavy and intense rainfall as far east as Groote Eylandt, are likely to precede the arrival of the cyclone itself.

The worst conditions are expected to occur in Darwin in the middle of the day, into the afternoon.

"There may be periods during the day where conditions seem to ease — and this is typical during a cyclone event — but it will be temporary, so do not assume that the danger has passed until you have been advised that it has," she says.

While conditions in Darwin have been relatively calm today, Ms Gamble says the weather is expected to worsen in the early hours of Saturday, continuing into Saturday evening.

Gales of around 90 km/h are expected in the Darwin area, she says, most likely during the middle of the day and the afternoon.

Ms Gamble confirms Tropical Cyclone Fina is set to reintensify to a category two system as it gets closer to the NT coast.

Heavy rain and strong winds are expected to impact communities in the warning zone further inland and west over the coming days.