Firefighters are facing heightened fire risks as heatwave and stormy conditions sweep across parts of the nation.

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.

On Sunday, people were urged to leave Julimar, Moondyne, Chittering and Lower Chittering.

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.

The danger came as large parts of the state, including across the southwest land division around Perth, experienced hot and dry weather, the Bureau of Meteorology’s Miriam Bradbury said.

High fire dangers are in place for much of western WA, with three regions near Perth under extreme fire danger warnings.

Many areas experienced temperatures in the mid to high 30s and low 40s, as the state swelters through a heatwave expected to continue into next week, she said.

Conditions had improved for blazes on the fringes of Perth but WA Department of Fire and Emergency Services’ Shaun Champ said the elevated temperatures across the weekend would be “very trying” for operations.

“If a fire was to ignite, putting pressure on the current fires we have in the landscape with those strong easterly winds coming off the desert, it is going to put pressure on containment lines,” he told ABC Radio.

The potential for dry lightning in WA as well as parts of Tasmania and Victoria from Sunday risked new fires sparking.

“It continues to be a really sensitive situation for most of our fire impact areas,” the bureau’s Bradbury said.

Well-above-average temperatures and a severe heatwave developing along the west coast during the next few days will track south during the week.

Weekend heatwave warnings are also in place for parts of the Northern Territory, South Australia and Queensland.

A reverse situation is expected to unfold in the country’s east, with cooler weather and rain set to fall along the coast and across NSW.

A cold front will also cool down South Australia and parts of Victoria.

High fire danger and gale-force winds are forecast across much of Tasmania on Sunday.

Tasmania Fire and Emergency Services Commissioner Jeremy Smith said strong winds and isolated storms would compound the fire risk.

“A high fire danger rating means there’s a heightened risk of fires, which can become dangerous and spread quickly,” he said.

Tasmania has already experienced fires on its southern and east coasts this season, and although the threat has eased, warnings remain in place, with Dianas Basin and Peron Dunes to be avoided on Saturday.

—with AAP