Temperatures in the high 30s have been forecast in the area by the Bureau of Meteorology, along with gusty winds of 60-80km/h.

With these conditions forecast, the fire could spread quickly and be extremely dangerous and fire authorities have warned residents to have their fire plans ready and leave early.

The warning comes as a large-scale fire base camp is established in Victoria Park which will become home to more than 300 firefighters.

These locations are expected to be impacted by fire, spot fires and ember attacks or the fire may close major roads resulting in isolated communities.

The CFA has declared a total fire ban in the Mallee, Wimmera, South West, Central, North Central and Northern Country for Wednesday.

Anyone located in the area of Ampitheatre, Beaufort, Clunes, Elmhurst, Learmonth, Lexton and surrounds should leave early - leave tonight (Tuesday 27 February) or early tomorrow morning (Wednesday 28 February). Do not travel to these areas.

Do not wait until the bushfire spreads closer before moving to a safer location. The Bayindeen fire could grow significantly and may become uncontrollable.

If you do not leave today, you may become isolated and your route to safer locations may be blocked. Road closures may occur, including roads that have recently been reopened, if they are threatened or impacted by fire.

Do not rely on firefighting crews to protect you and your property.

If you are in the Ampitheatre, Beaufort, Clunes, Elmhurst, Learmonth, Lexton and surrounds area, move to a built up area like Maryborough, Ararat or Ballarat or another regional city outside the potential impact area.

These are areas that have been identified as defendable by emergency services.

Emergency services will advise when it's safe to return or travel to family and friends who are outside the area.

Before you travel, check that your planned route and destination are not currently under threat from fire. Do not travel into areas of Extreme or Catastrophic Fire Danger.

While travelling, monitor weather conditions by listening to local or ABC radio as conditions may change quickly.

Take care on the roads and drive to the conditions. Smoke from these fires may impact visibility when driving.

When you leave, take the following items with you:

If you have left, ensure you register with www.Register.Find.Reunite online: www.register.redcross.org.au - Extreme Weather Western Victoria 2024.

This service lets people know you are safe, that you have relocated away from the area, and is used by emergency services if evacuations are required. People leaving early, or who relocate from the fire area, are asked to register as soon as possible.

If you are in any area with a Catastrophic or Extreme Fire Danger Rating, it is critical you monitor warnings and stay informed. You should follow the instructions of emergency services.

Check VicEmergency for warnings frequently. If you are currently in an area that is under a warning you must follow the instructions in that warning.

The bushfire that started in Bayindeen on Thursday is not yet under control and remains active.

Emergency services have released a map of potential fire impact for the Bayindeen - Rocky Road fire as they make last minute preparations ahead of Wednesday's extreme weather conditions.

The potential impact area is a ring around the existing 20,500 hectare blaze stretching past Elmhurst and Lamplough to the north, as far as Clunes to the east, as close to Ballarat as Learmonth, Blowhard and Burrumbeet, as far south as areas just past Lake Goldsmith, and west to Mount Langi Ghiran.

While there are no fires in Ballarat, the base camp will act as a hub for movements to fire grounds and could be in use for up to a month.

Ballarat Incident Control Centre deputy incident controller Paul Bates said the Bayindeen-Rocky Road fire that began last Thursday was still not under control and Wednesday would be a "significant risk day with pretty severe fire behaviour" expected.

On Monday there were 900 firefighters and 20 aircraft working the fire, which has grown to more than 20,000 hectares with a fire edge of 164km.

"In advance of Wednesday we are constructing as much control line along the fire edge as we can. We are building control lines with bulldozers and graders, burning unburned fuel between the control line and fire edge ... and using all our resources including about 20 aircraft to directly attack any spots," Mr Bates said.

With the extreme fire risk there is also the potential for new blazes to break out separate from the large bushfire burning for almost a week.

"We encourage people to keep up to date with the VicEmergency app, to listen and heed those warnings and be really conscious of what is going on," Mr Bates said.

"If you've got a fire plan, enact it. If you're going to leave early, I strongly suggest leaving Tuesday evening or night.

"Leaving at the last minute is not a wise decision."

CFA chief officer Jason Heffernan urged property and home owners to prepare ahead of Wednesday's extreme fire conditions - including mowing lawns, moving wood piles, clearing branches, cleaning gutters and simple precautions such as moving combustible front and back doormats.

The Victoria Park base camp began to take shape on Monday, with road closures to occur in and around the park.

"The City of Ballarat is pleased to offer our support to the CFA who are doing an outstanding job battling the blazes that are yet to be brought under control," Ballarat mayor Des Hudson said.

"We ask people who live and travel in the Victoria Park precinct to be mindful of the camp that's quickly being established. We are trying to minimise the impacts on regular park users but roads into the park will need to be closed. Please be patient and understanding of the important work that's being done to assist our emergency support agencies.

"And with extreme weather conditions predicted for Wednesday, it's also a timely reminder for us all to ensure our properties are fire ready - ensure your grass has been slashed and your gutters cleared. We all need to play our part."