Assessment of Spatial and Temporal Trends Influencing the Occurrence of Frost After Budburst

Abstract

Background and Aims: The occurrence of frost after budburst is extremely damaging to the wine industry. This research aims to understand frost risk after budburst in Australian wine-growing regions amid a changing climate, investigating the factors driving frost events and their implications for grape production.

Methods and Results: Using historical climate data and modelled budburst date, this study assesses the spatiotemporal trends in frost occurrence after budburst from 1910 to 2019. This research demonstrates that recent climate variability and changes in frost risk are complex and vary between wine regions. Whilst the majority of wine regions showed no significant trend over time, some regions—predominantly in SA and WA—exhibited a decreasing frost risk after budburst. Conversely, some inland wine regions demonstrated an increasing trend in frost potential days, suggesting that frost risk may be worsening in these regions. The influence of climate drivers—ENSO, IOD and SAM—on frost occurrence was also evaluated, highlighting ENSO and IOD as significant factors in Eastern Australia, particularly during positive phases when drier conditions increase frost likelihood.

Conclusions: This research demonstrates that recent climate variability and changes in frost risk are complex and vary between wine regions. The assessment of the historic datasets showed varied trends in frost risk potential (both increasing and decreasing trends), while modelling indicated a reduction in overall frost risk. Ongoing monitoring and adaptation efforts are essential to address regional disparities and ensure the resilience of the wine industry to changing climatic conditions.