High fire danger across the nation keeps risks live

Fire crews are facing the prospect of new bushfires as Australia experiences heatwaves in the west and cool fronts in the east.

Western Australia is in the grips of a heatwave, with Perth forecasted to reach 39C and surrounding suburbs could exceed 40C on Sunday, according to the Bureau of Meteorology.

"This really prolonged hot period is driving severe heatwaves across parts of southwest WA, including around Perth, and that's likely to continue until around Tuesday," meteorologist Miriam Bradbury told AAP.

Most of the state will be under high fire danger on Sunday, with parts of the southwest near Perth facing extreme risks.

An emergency evacuation alert for residents in parts of Bowes, Howatharra and Oakajee north of Geraldton was downgraded but people have been told to avoid the area.

There is also a risk of thunderstorms across the state which could bring dry lightning, sparking more fires, Ms Bradbury said.

"It continues to be a really sensitive situation for most of our fire-impacted areas, a really challenging period, unfortunately, continues," she said.

A sweeping cold front in Australia's east brings cool, showery conditions across Tasmania on Sunday but also a risk of fires.

"We're getting strong winds as well, even behind this front, and that means fire danger ratings are going to remain pretty high for parts of the southeast of the country over the coming days," Ms Bradbury said.

Strong and gusty winds are expected over Tasmania's Furneaux Islands on Sunday, bringing extreme fire danger.

"It's the drier conditions and stronger winds that are really ramping that fire risk up," Ms Bradbury said.

High fire risks are also in place for many parts NSW and one South Australian region on Sunday.