An above-average bushfire risk is forecast for Perth and large parts of the Midwest-Gascoyne, Pilbara, South West and Great Southern regions.

Heavy rainfall in recent months has increased grass fuel loads in parts of WA, according to the 2021 National Seasonal Bushfire Outlook.

Daily temperatures are predicted to be above average for most of the state.

"Rainfall in recent months has increased fuel loads, which has increased the risk for areas with woody vegetation such as the South West Land Division," WA Fire and Emergency Services Commissioner Darren Klemm said on Thursday.

"We're urging the public not to be complacent because of the high rainfall we've seen this year - everyone should develop a bushfire plan now."

Normal fire conditions are expected for the rest of WA, with the far north predicted to receive average rainfall during the wet season.

Australian meteorologists have declared a La Nina weather event is under way, with the country's wettest spring in 10 years to continue into summer.

La Nina is part of a cycle known as the El Nino-Southern Oscillation, involving a natural shift in ocean temperatures and weather patterns in the Pacific Ocean, bringing a greater risk of damaging tropical cyclones and flooding.

However, the Bureau of Meteorology says the impacts from La Nina in WA will be "significantly less" than in the eastern states.

The Wooroloo bushfire in Perth's northeast in February burnt through almost 11,000 hectares of bushland, destroying 86 homes as well as livestock, sheds and machinery.

Daniel Gunter Preuss, 40, has been charged with failing to take due care while in charge of an ignition source and breaching a total fire ban. It's alleged his use of an angle grinder sparked the devastating blaze.

A bushfire task force will operate seven days a week from November to April, with WA police officers patrolling hot spots.

Rewards of up to $50,000 are being offered for information regarding arsonists.

Australian Associated Press