A race meeting scheduled for Yarra Valley in Victoria this week will begin in the morning in a bid to avoid the forecast hottest part of the day.

Racing Victoria says because of the predicted 40 degrees, Friday's Yarra Valley meeting will begin two hours earlier than originally planned with the opening race at 10.30am.

The final race on the nine-race program is scheduled for 2.40pm.

The move has been made following advice from the Bureau of Meteorology that the hottest part of the day will be at 5pm.

On Monday it was decided to shift Wednesday's Caulfield city meeting from a twilight timeslot to an 11am start because of the forecast for hot weather while races for Wednesday's Bairnsdale meeting were also brought forward one hour.

Friday's scheduled twilight meeting at Morphettville in South Australia will go ahead beginning at 5pm but the number of races has been reduced from nine to seven.