Most of northern and central Victoria has a greater than 70 per cent chance of above average rainfall in June and July. However, much of Gippsland has roughly equal chances of being wetter or drier than average.
The temperature outlook for winter is consistent with the rainfall outlook. Parts of the northwest have a slightly increased chance of cooler days during June to August, while days are likely to be warmer than average for parts of the east, with no strong push either way for the rest of the State.
Nights are likely to be warmer than average in most parts, with extra cloud overnight stopping temperatures from rapidly dropping. The highest likelihood is in the north and the chance of warmer than average minimum temperatures decreases gradually further south.
Victoria's average rainfall for June ranges from around 20 mm in the northwest, to over 100 mm in elevated areas and exposed parts of the south, and more than 200 mm in parts of the Alps. The average rainfall is usually slightly higher for July for most locations. Rainfall over Victoria typically increases during winter—long-term average monthly rainfall is at its highest in August.
The main drivers for the wet winter outlook are the conditions in the tropical Pacific and Indian oceans. The international climate models surveyed by the Bureau of Meteorology are predicting a negative Indian Ocean Dipole may develop in mid-winter. And they also show signs of a La Niña-like pattern developing in the Pacific Ocean.
Both the negative Indian Ocean Dipole and La Niña increase the chance of above average rainfall for most of Victoria. Even if some of the indicators in the Pacific Ocean, or the atmosphere above it, don't exceed La Niña thresholds, parts of eastern Australia can still observe some La Niña-like effects, including enhanced rainfall.