Race meetings on the NSW South Coast and in the Riverina region have been called off because of bush fires and smoke haze while others in the state are under threat from extreme heat.
The Sapphire Coast (Thursday) and Moruya (Monday) are off while Tumut on Saturday has been rescheduled for January 18.
Road closures are also affecting meetings to the south.
Racing NSW will invoke a Level 2 Hot Weather Policy for Muswellbrook on Friday with the temperature forecast to reach 41 degrees.
The same level will be in force at Albury on Friday with a forecast 40 deg and concern over the poor air quality which will continue to be monitored.
Gilgandra in the central west is also in doubt and if the forecast for 43 deg remains it will be called off.
The Hot Weather Policy means horses need to be on course 90 minutes before they race to have time to cool down with pre-race parades shortened.
