Climate drivers of red wine quality in four contrasting Australian wine regions

Background and Aims: The understanding of the links between weather and wine quality is fragmented and often qualitative. This study quantified and integrated key weather variables during ripening, and their influence in red wine quality in the Hunter Valley, Margaret River, Coonawarra and Barossa Valley. Methods and Results: Long-term records of published vintage scores were used as an indicator of wine quality. A χ² analysis was used to compare good (top 25%) versus poor (bottom 25%) vintages in relation to the frequency of defined weather conditions. Using maximum temperature as an example, better quality was associated with temperatures above 34°C throughout most of ripening in the Hunter, below 28°C in early January in the Margaret River, 28-33.9°C towards harvest in Coonawarra, and below 21.9°C in late January and early February and 28-30.9°C towards harvest in the Barossa. Conclusion: Our quantitative assessment allows for the timing and magnitude of weather influences on wine quality on a regional basis. Significance of the Study: The improved specificity of the links between weather and wine quality will help in the development of a risk analysis framework for wine quality across Australia.