A cool change is expected to provide relief for Victorian firefighters who have managed to contain a blaze that has been burning in the state's southwest for a week.

Firefighters had contained the Kentbruck blaze by 6pm (local time) on Thursday, managing to backburn 4500 hectares of land in inaccessible and difficult terrain within the day.

Country Fire Authority (CFA) spokesman Chris Clugston said the backburning brought the size of the blaze to 11,890 hectares.

"Some very excellent work was done by firefighters yesterday, burning out unburnt sections inside the control lines," he said on Friday.

A wind change expected to begin sweeping in from the state's west from mid-morning on Friday was expected to reduce temperatures and cool the fire down.

Mr Clugston said 50 firefighters remained at the scene consolidating and patrolling the control line.

Another fire in bushland at Goroke in the Wimmera region that started on Tuesday became active again on Thursday, but was contained by the afternoon.

A total fire ban has been declared across Victoria amid extreme fire danger conditions in the Wimmera and north central districts, and severe ratings across the rest of the state.

Temperatures are expected to pass 40C in some parts of the state on Friday.

- AAP