Melbourne's weather is set to play a role in the preparation of the Moonee Valley track ahead of the Cox Plate.

The weather bureau says there is a 40 per cent chance of 0-3mm of rain falling on Saturday.

Moonee Valley track manager Marty Synan said as Saturday's Cox Plate meeting draws closer he will make a decision on how much water will be applied.

He plans to water on Thursday morning ahead of the Manikato Stakes meeting on Friday.

"Hopefully the track will be a good four on Friday morning and get up to a good-three for the Manikato and then we'll assess what the weather does," Synan said.

"If we get some rain we may not water. If we don't we might water after the Manikato and get it to that good four for Saturday morning.

"It may stay a good four all day depending on the weather or improve to a good three, but my main goal is leaving it a good four all day."

Synan said the rain that fell in Melbourne on Caulfield Cup day was perfect for the track.

He said in his 22 years at the club he has not seen the track in better condition.

The Moonee Valley rail will remain in the true position for Friday night and Saturday with the Cox Plate race 17 of 18 in a 24-hour period.

"We had a bit of criticism a few years ago when we moved it out but we've made the decision to leave in the true for both," Synan said.

"It's our third year doing it and I think it's working, so we'll stick with what works."