South Australian racing officials have decided to push back a pre-Christmas race meeting at Morphettville because of extreme heat.

A twilight race meeting was scheduled for Morphettville on Friday but the seven races have now been moved to Monday afternoon.

A meeting at Dubbo in NSW on Saturday has been abandoned because of a predicted 45 degrees and no suitable alternative dates available.

Saturday's Sydney metropolitan meeting has been moved from Warwick Farm in the west to Randwick which is expected to be up to 10 deg cooler.

Racing officials in NSW, Victoria and South Australia have been juggling start times of recent meetings to try to avoid the hottest parts of the day.