Weather station staff to be evacuated as cyclone looms

North Queensland residents are on high alert, with Tropical Cyclone Jasper set to impact the coast between Cooktown and Townsville by mid-next week.

It has intensified into a category 4 system with sustained winds of 195km/h and gusts of up to 270km/h.

"This is a strong system," the Bureau of Meteorology's Sarah Scully said.

It was about 1200km off Cairns on Friday, slowly tracking southwards.

"We can't rule out over the next 12 hours or so that it may intensify into a category 5 as the atmospheric conditions are supportive of tropical cyclone development," Ms Scully said.

The large system's course sparked evacuation plans for the bureau's Willis Island station, about 450km off Cairns in the Coral Sea.

A rescue helicopter is on standby to pick up four staff members on Saturday, with the station on the tiny island now in the cyclone's path.

A bureau spokesperson told AAP the remote station was built to withstand a category 5 cyclone but staff safety was the priority.

"Logistics are in place to evacuate the four bureau staff from Willis Island tomorrow morning," the spokesperson said.

Jasper is set to weaken at the weekend but is expected to intensify again into a severe tropical cyclone as it approaches the north Queensland coast next week.

A cyclone watch - a warning issued when coastal impact is expected within 24 and 48 hours - could happen as early as Sunday.

It is expected to weaken to a category 2 by Monday.

"We can't rule out that it is going to re-intensify before making landfall," Ms Scully said.

"However there is high uncertainty with this system and it's really important that you stay up to date with our latest forecasts and warnings."

Ms Scully said winds between Townsville and Mackay across coastal waters would start to strengthen by Saturday and heavy showers were forecast from Monday.

Queensland Police's Acting Deputy Commissioner Shane Chelepy urged residents who lived between Mackay and Cooktown to start preparing their emergency kits.

The system is the first tropical cyclone to form in Queensland waters in December in an El Nino year.

"It's unusually early for Queenslanders," Emergency Services Minister Mark Ryan said of Cyclone Jasper's arrival.

"Cyclones can obviously have devastating impacts on community, property and life.

"This is not a practice; this is not a drill.

"This is the real deal ... continue to pay attention to authorities."

Severe heatwave conditions in the far north and southwest are set to ease as the cyclone approaches, bringing widespread showers next week.

"Tropical Cyclone Jasper is quite a large system which means that it does have quite a lot of cloud bands associated with that, bringing showers, rain and thunderstorms," the bureau's Laura Boekel said.

The state disaster centre has been moved to alert level, with preparations in place with local and district co-ordinators spanning Mackay to Cairns.

Queensland Fire and Emergency Services crews are on standby, including swift water rescue operators.

"When we get a little bit more certainty as to where this cyclone may cross, we will be deploying additional resources into those areas to help the local emergency services in the event that this turns nasty," QFES's Kevin Walsh said.

Australian Associated Press