Tropical low has Qld on cyclone watch

A tropical low over the Gulf of Carpentaria is a "moderate" chance of turning into a tropical cyclone, forecasters say.

The Bureau of Meteorology is closely monitoring the slow-moving low, which is likely to dump hundreds of millimetres of rain on Queensland's Gulf and near the Northern Territory coast even if a cyclone doesn't eventuate.

"At this stage it's a moderate risk of turning into a cyclone (in the coming days), we are watching it very closely 24/7," meteorologist Dean Narramore told AAP.