A cyclone watch was upgraded to a warning on Wednesday morning, for coastal and island communities from Port Douglas, north of Cairns, south to Mackay.

The weather system is about 590 kilometres east-northeast of Cairns and 600km northeast of Townsville, and is moving towards the coast at 9km/h.

At this stage forecasters expect it to cross the coast, possibly as a low-strength cyclone, on Friday morning, between Tully, south of Cairns, and Townsville.

A cyclone watch remains in place for coastal and island communities from Mackay south to St Lawrence, and inland through the eastern interior north of Clermont.

A strong ridge of high pressure is combining with the low to generate gales along much of the east coast between Port Douglas and Mackay.

A Bureau of Meteorology map showing the path of the potential cyclone.

Winds are expected to build to damaging gusts of 120km/h from Wednesday afternoon or evening, and will continue on Thursday and Friday.

Forecasters are also warning of heavy rain, which may cause flash flooding, for coastal and inland parts of the north tropical coast and tablelands, Herbert and Lower Burdekin and the Central Coast and Whitsundays districts from Wednesday afternoon.

A dangerous storm tide is also expected between Port Douglas and St Lawrence, mainly on the high tide over the coming three days.

“Large waves may produce minor flooding along the foreshore. People living in areas likely to be affected by this flooding should take measures to protect their property as much as possible and be prepared to help their neighbours,” the bureau said on Wednesday.

The next severe weather advice will be issued at 11am.