The likelihood of rain will throw another spanner in the works of an already-complex World Rally Championship finale set to begin on Friday.

Coffs Harbour, on the NSW north coast, will host its seventh Rally Australia across the next three days but for the first time the title is up for grabs on the dusty forestry roads that surround the city.

Sebastien Ogier is gunning for a sixth-straight world title and holds a slender three-point lead over Thierry Neuville, while Ott Tanak is 23 points back and, with 30 points up for grabs, still a mathematical title chance.

Rain is forecast to fall on all three days of racing, which could either settle or slosh the usually dusty roads for what is the tightest WRC finish in 15 years.

As series leader, Ogier will be the first man to leave on Friday morning and in dry conditions would ironically be forced to sweep the path clear for his rivals.

For that reason the Frenchman, in his Ford swansong before departing for Citroen next year, welcomes the prospect of wet weather.

“If it’s real rain then it’s super tricky with a lot of changes in grip and a lot of challenges,” he said.

“But I think it’s better this way, it’s better for everybody – if it’s dry then the leader struggles.

“I don’t want to think too much about it, I know how much the weather can change here so, until I see it, I don’t want to believe in it.”

The title race isn’t likely to be decided until Sunday’s Power Stage but Ogier knows he could lose it on Friday.

“Saturday is much worse with much more loose (gravel) on top of the road,” he explained.

“So it’ll be important to be quick (on Friday) to help pick up a better place on the road for Saturday.”

Racing will take place on local roads and forestry trails on all three days, while an action-packed city circuit bordering Coffs’ marina and jetty will be used on both Friday and Saturday afternoons.