A cyclone warning is now up in the Northern Territory coast and residents are urged to prepare and not be complacent.

The Bureau of Meteorology (BoM) at 5 PM (CST) upgraded its cyclone advice for the coastal areas from Daly River mouth to Point Stuart, including Darwin and the Tiwi Islands, from a cyclone watch to a cyclone warning.

The agency said that though this may not be as strong as Yasi, but residents must prepared with a cyclone kit and evacuation plans made.

According to a related report on the Sydney Morning Herald, a slow-moving tropical low, about 85km southwest of Darwin, continued to dump torrential rain across the Top End as forecasters warned it was "reasonably probable" that the system would develop into a category one cyclone when it reached the coast on Wednesday.

BoM regional director Andrew Tupper said the cyclone could strengthen above a category one, but unlikely to be as strong as Yasi.

"With Yasi we were able to see very clearly a long way out that an intense cyclone was likely to hit the Queensland coast," he told reporters in Darwin.

"At the moment we don't have those fears for the NT coast but we are mindful of the unpredictability of cyclones up here."