Firefighters are focused on preventing deaths as Victoria braces for potentially catastrophic weather conditions.

The Wimmera region’s fire danger rating for Wednesday was upgraded from extreme to catastrophic.

Extreme fire danger is also predicted for five of Victoria’s nine total weather districts mid-week.

The Mallee region was slated to reach mid-40C and get winds of up to 45km/h on Wednesday while other parts of the state were also expected to creep into the 40Cs.

Country Fire Authority deputy chief Garry Cook said the conditions were all there on Wednesday to encourage bushfires.

“The air mass is really dry, it’s got a strong northerly wind pulling all that hot (and) dry air down over Victoria, and then a blustery southwesterly change will come through late in the evening,” Mr Cook told AAP.

“Our job now is to – where we can – prevent anything from starting, and that’s (also) the community’s job.”

About 500 firefighters are battling the wild Bayindeen blaze, northwest of Ballarat, which had burned through more than 21,300 hectares as of Tuesday morning.

Crews were working day and night to try to get a consolidated line around the massive blaze but the steep landscape, unfit for fire trucks, made it difficult to tackle, Mr Cook said.

Winds swinging to the north were expected to put pressure back on the fire’s southern edge through Tuesday and the Country Fire Authority did not expect to have the blaze under control by Wednesday, the deputy chief said.

Firefighters have worked hard to deepen the control line on the southern side of the Bayindeen fire in recent days, and NSW Rural Fire Service personnel were expected on Tuesday to help with the battle against it.

“We will have a significant amount of resources deployed, both aircraft and ground crews, for Wednesday to there – but we’re also setting ourselves up so that we’ve got resources for new (fire) starts as well,” Mr Cook said.

“There is a potential … for some lightning later in the afternoon or the evening as the change progresses across the state.

“We’re hoping that doesn’t occur but if it does, it’s likely to be dry lightning.”

Crews were tracking weather conditions hour by hour with the Bureau of Meteorology, Mr Cook said.

He warned Victorians against risking starting fires while the danger was so high, including by operating machinery in vegetation, mowing, welding or grinding.

“Our primary objective is to make sure we don’t lose any lives, and the community so far … have been heeding the warnings,” Mr Cook said.

“We’ve got another really tough day to go and we just ask the community to continue to do their bit.”

Watch and act warnings remain in place for residents of Amphitheatre, Elmhurst, Raglan, Waterloo and other areas, warning locals that it is still unsafe to return.

Source: AAP