Firefighters battling Victoria’s coal mine fire are preparing for a strong wind change that has the potential to fan a blaze that has already lasted more than three weeks.

A forecast change, expected to hit the area after 9am (AEDT), has the potential to also blow smoke back over Morwell, incident controller Bob Barry says.

These are similar to conditions experienced last Tuesday, when the blaze escaped from the mine and headed towards the power station, before it was brought under control.

While firefighters have made good progress in recent days and brought 85 per cent of the blaze under control, hopes to contain the fire by Sunday depend largely on Wednesday’s windy weather.