Tropical Cyclone Victoria, in just an overnight, has morphed into a Category Three system, as it further packed in strength off the north-west coast of Western Australia.

Located 555 kilometres south south-west of Christmas Island, the system was seen moving in a southerly direction in the open water.

The system has affected the weather on Christmas Island.

"Squally conditions may be experienced (on the island) until Thursday under the influence of the system," the Bureau of Meteorology said.

However, Cyclone Victoria could disrupt the weather at Perth over the coming weekend as the mass of unstable tropical air continues to go southwards. Rain showers have been forecast for Saturday for Perth.

The BoM said it does not see the tropical cylone making landfall.

"Later on in the week and into the weekend, what's left of the system we might get some light rain or some shower activity over southern parts of the state," BoM's Brad Santos said.

"We're not expecting any impacts from the tropical cyclone on the WA mainland."

The weather in Perth forecast for the next seven days: