Bush sprinter Big Money's path into a weight-for-age race that signals the start of the Sydney autumn carnival is under threat on two fronts.

One of 10 entries for the Summer Sprint at Randwick on Saturday, Big Money is also nominated for a Muswellbrook barrier trial on Thursday.

But trainer Rodney Northam admits he could scrap both options if the weather forecast at the end of the week is right.

Temperatures as high as 40 degrees are tipped for the Hunter Valley and rain is predicted in Sydney.

"I worked him this morning as if I was going to Sydney, but I'll just see," Scone-based Northam said.

"I was originally just going to trial him at Muswellbrook on Thursday but the weather looks like being really hot.

"This race (on Saturday) looked a bit light on but I'm a bit fifty-fifty about which way I should go.

"I'm quite happy with where he's at but a lot is depending on the weather."

Northam had intended to set Big Money for a first-up weight-for-age assignment in the Expressway Stakes at Randwick on January 30 on the back of a barrier trial and an exhibition gallop between races on his home track.

Koby Jennings, a heavyweight apprentice who has a 3kg allowance, is on standby to ride Big Money on Saturday.

Jennings's claim will reduce Big Money's handicap to 60kg - a winnable weight for a horse which has raced consistently at stakes level for two seasons.

Big Money has been away from racing since finishing midfield in the Stradbroke Handicap.

It was his third unplaced run at Group One level during the Queensland winter carnival but Northam said the six-year-old didn't disgrace himself in Brisbane.

"He raced well last prep without collecting any money and we'll see if we can get him a winning frame of mind early on," Northam said.