UPDATE: A SERIOUS bushfire is burning out of control west of Port Lincoln in South Australia.

The Country Fire Service said the fire at Mungerowie Scrub on the Lower Eyre Peninsula near Big Swamp may change and threaten the safety of locals.

The CFS expects a change in the wind direction or fuel type at about 1pm may cause the fire to change direction or accelerate and move towards Port Lincoln City.

Three fire ban districts - Eastern Eyre Peninsula, Lower Eyre Peninsula and Yorke Peninsula - have the highest forecast danger rating of catastrophic, and 11 are rated either extreme or severe.

Metropolitan Adelaide is the only district exempt from the total fire ban and has been given a high fire ban rating.

Water bombers and extra fire crews are on standby and national parks, reserves and 17 state schools and preschools have been closed for the day.

The weather bureau says strong winds have been forecast, while temperatures could reach the high 30s.