Since the mid-1990s, climate conditions across Victoria have been persistently drier than the long term average conditions. This paper quantifies the change in climate regime across Victoria that has been observed since 1997. The recent average annual rainfall conditions experienced across almost 60 rainfall gauge locations across the state are compared to the long term historical conditions (1961-1990). This analysis shows that average annual rainfall has reduced across all study locations, with a reduction of up to 24% in some locations.
On a seasonal basis, the changes in rainfall over the past 13 years have been varied. The changes to average summer rainfall conditions have been varied, with reductions of up to 21% in the central region of the state but increase in average rainfall across much of western Victoria and parts of Gippsland. Average autumn conditions have been significantly reduced since 1997, with some parts of Victoria experiencing almost 50% less autumn rainfall compared to the 1961-1990 period. The reduction in autumn rainfall is more pronounced for northern areas of the state. Average winter rainfalls have been less than historical conditions for central and western parts of Victoria, but have increased in the Gippsland region. Average spring rainfall conditions are slightly below the long term average in most areas of Victoria, although slight increases are observed in isolated areas of northern Victoria.
Such significant changes in rainfall conditions have implications for the long term planning and management of the state’s water resources.