The NSW race meeting scheduled for Goulburn has been postponed after a wind change reduced air quality in the area to hazardous levels.

Racing officials made the decision to call off Friday's eight-race card mid-morning when the effects of smoke from nearby bush fires worsened.

A number of NSW race meetings have been postponed or abandoned in recent weeks because of the poor levels of air quality as a result of bush fire smoke.

A race card scheduled for Dubbo on Saturday has also been lost with a forecast for extreme temperatures, while Sydney's main metropolitan meeting has been switched from Warwick Farm to Randwick to avoid the worst of the predicted heat.