Much of western Victoria is close to, or has passed, their average October rainfall after heavy falls last week. It has been a wet spring so far for the south-west with more than 100 mm along parts of the coast for October to date, following a wetter than average September in the area. But September was very dry in Central Gippsland and while they missed out on the lion's share of last weeks rainfall, there is more rain on the way for eastern Victoria this weekend.
The rest of October is looking wetter than average for much of the eastern two-thirds of Australia, including northern and eastern Victoria but the signal is much stronger over parts of north-east NSW and southern Queensland than it is over Victoria.
The rainfall outlook for November to January shows that most of Australia is likely to be wetter than average. For Victoria, the highest chances of above average rainfall are across the north and north-east. Days are likely to be warmer than average along the coast and in parts of central and western Victoria, while nights are very likely (more than 80% chance) to be warmer than average for the whole state.
A La Niña pattern in the tropical Pacific is the main culprit for the wet outlook. The indicators climatologists look for in the oceans and the atmosphere (including sea surface temperatures, the trade winds, pressure patterns and cloudiness) are showing coupling between the ocean and the atmosphere, increasing the chance of La Niña lasting for several months.
The Indian Ocean Dipole index has been bouncing around lately, which means although we've seen a negative Indian Ocean Dipole pattern at times in recent months, it hasn't been consistent. The chance of a full-blown negative Indian Ocean Dipole event this year has declined, noting that the Indian Ocean Dipole typically breaks down in late spring or early summer.
Both La Niña and negative Indian Ocean Dipole events typically increase the likelihood of above average rainfall across much of Australia during spring, with La Niña's wet influence extending into summer for eastern Australia.
Root zone soil moisture is mostly average to above average across the state for this time of year after the recent rain. High soil moisture combine with a wet outlook increases the risk of flooding in the months ahead. In Australia, flooding is the second most deadly natural disaster after heatwaves.