Caulfield track manager Jason Kerr has admitted the surface was firmer than he would have liked on Rupert Clarke Stakes day and he will be irrigating leading up to the Guineas meeting.

With a forecast of 25 degrees predicted for Saturday, Kerr said he would prepare the track to have some moisture in it.

"We've got a reasonably good forecast," Kerr said.

"Showers early in the week and then fining up for a nice day on Saturday.

"We put eight mils of water on yesterday and depending on the rain for the rest of the week we'll likely put some more irrigation on."

Kerr said the track was firmer than ideal for the last meeting on September 28 and with a late finish of 6pm for the next two Saturdays he said more moisture would be left in the track earlier in the day.

He said he would be aiming for a penotrometer reading of between 5.3 and 5.35 on Saturday morning ahead of the program featuring four Group One races.

"It was a bit firm for a few on Rupert Clarke Stakes Day," Kerr said.

"With 24 or 25 degrees, somewhere in the 5.3 to 5.35 range is about where we want to be.

"If it's any higher it's into the Dead 4 range and if you get a bit of an overnight dew and not as hot a day as they tipped, you get it stuck in that range with a little bit too much moisture in it."

Kerr said there was only one penotrometer reading a day, taken in the morning, but in the past 12 months a moisture sensor had been installed at Caulfield providing valuable data.

When the track is resurfaced following the Caulfield Cup, 20 moisture sensors will be installed around the track.

"After the resurface we're going to put in a fixed system where 20 moisture sensors will be put around the track which will feed back to a web-based system," Kerr said.

"That will give us a running average every half hour which will give us terrific information on raceday which can then be displayed on the big screen at how quickly, or not so quickly, the track is drying out.

"We'll hopefully have that up and running in February or March when we get back next year.

"I think that will take a lot of that discussion away."