Tropical Cyclone Seroja looms off WA north

An urgent warning has been issued to holidaymakers camping or travelling in caravans in Western Australia's north as a tropical cyclone looms.

Tropical Cyclone Seroja is tracking south from its current position 670km northwest of Karratha and is expected to make landfall as early as Sunday.

A cyclone advice alert has been issued by the Department of Fire and Emergency Services for an area spanning from Onslow to Jurien Bay in the state's Pilbara, Gascoyne and Mid West regions.

Acting DFES commissioner Craig Waters said there were many holiday-makers in the area, many of whom would not have experienced a cyclone before.

"Recent rainfall and flooding has already battered the northern half of WA during the current cyclone season," he said on Thursday.

"If you're in a tent or caravan, you are simply not protected against the damaging winds that may hit the region.

"Some roads in the area are still undergoing maintenance to repair damage from recent flooding events and Tropical Cyclone Seroja has the potential to cause further damage making roads unpassable for days, if not longer."

The DFES is urging travellers to reconsider their plans and stay up to date with the latest emergency information.

""The size of this potential impact area is another reason to be prepared, because you may need to travel some distance before you are out of harm's way," Mr Waters said.

A separate tropical low lying well to the south of Christmas Island could also develop cyclone intensity in coming days as it tracks east.

The Bureau of Meteorology say it's possible the two systems will rotate around each other when they get close enough, an interaction known as the Fujiwhara Effect.

"Seroja is expected to bring a relatively brief but intense period of dangerous weather to the west coast of WA ... most likely between Jurien Bay and Carnarvon," the bureau said.

"This is a rare event for people on the west coast of WA.

"There is likely to be destructive winds, very heavy rainfall and higher than normal tides close to Seroja's path."