Tropical Cyclone Errol was upgraded to a category-two system early on Wednesday after a low-weather system formed into a category one late on Tuesday night, the Bureau of Meteorology said.
Cyclones are given categories based on their average maximum wind speed with one being the weakest and five the strongest.
Category two systems have destructive winds with an average maximum average wind speed of 89–117 km/h.
Category three cyclones bring very destructive winds up to a maximum average of 159km/h.
"By the time we get to tomorrow morning, possibly looking at an intensity category three," meteorologist Helen Reid told AAP.
"It is moving further west at the moment, but that intensification will also come with a bit of a switch of a direction down towards the southeast and then heading back towards the mainland."
Late on Wednesday morning, Errol was moving west over waters about 510km northwest of Broome.
Errol is not expected to impact the WA coast in the next 48 hours but wind warnings could be issued as early as Thursday morning for parts of the WA coast and inland areas, Ms Reid said.
Severe weather warnings for heavy rainfall may also be issued.
"When it does start to turn it will be under the influence of slightly different upper atmospheric dynamics, and that will help it turn as well as maybe interrupt some of that intensification process," she said.
"It might well contribute quite likely to a weakening of the system as it heads towards the coastline again."
If it makes landfall, Errol would be the third cyclone to impact WA after Dianne crossed the coast in late March and Zelia made landfall in February.
Zelia reached the coast as a category-four system, bringing widespread rainfall and damage to infrastructure.
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