Relief as hundreds evacuated from path of cyclone

About 500 people overall are set to make a Darwin high school gymnasium their new home in the coming days as they ride out Narelle's wrath.

The cyclone has weakened since crossing the far north Queensland coast early on Friday but is set to intensify in the Gulf of Carpentaria before entering the NT late on Saturday.

Evacuee Natasha Nundhirribala told AAP outside the gym members of her community were feeling safe after fearing the wind and rain the cyclone would bring.

She said many had wanted to stay in their homes.

"We're near the beach and the tide is going to rise up and our jetty will probably be underwater," she said.

Ms Nundhirribala said police still stationed in Numbulwar would watch out for the pets residents had left behind.

Steve Wilfred, who evacuated with his wife and five children, said the very high winds and heavy rain would make it dangerous and he was worried for his three dogs and two cats.    

He told AAP the evacuees hoped to be back in their community by Monday to start cleaning up.

The cyclone is set to pass Groote Eylandt on Saturday night with wind gusts up to 200km/h - strong enough to cut power, cause structural damage and fell trees.

Narelle was set to weaken as it crossed the NT coast to become a category two system and eventually a tropical low as it quickly moved west, the Bureau of Meteorology's Shenagh Gamble told reporters in Darwin on Friday.

Gulf communities, including Groote Eylandt, are on cyclone warnings to shelter in place and activate their emergency plans.

A major flood warning has been issued for the Katherine River, which is set to rise quickly from Sunday afternoon.

Nearby Katherine has been in clean-up mode since suffering its worst floods in almost 30 years but Narelle's arrival has sparked fears it will be inundated again. 

Flood watches have been issued across the Top End, with heavy rain expected to cause rivers and creeks to rise.