The pattern of seasonal temperature odds across Australia is a result
of recent warm conditions in the Indian Ocean and an increasing level
of warmth in the Pacific. Of the two, the influence from the Indian
Ocean is greater for this particular outlook.
The chance that the average winter maximum temperature will exceed the
long-term median maximum temperature is around 60 to 65% for most of NSW, Victoria
and SA (see map).
This means that for every ten years with ocean patterns like the current, about six
years would be expected to be warmer than average in terms of daytime
temperatures averaged over winter, while about four would be expected to be cooler.
The chances of a warm season are even higher (65 to 70%) in western SA,
but a slightly lower (55 to 60%) along the east coast of NSW and in most of Tasmania.
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During winter, history shows this
effect on maximum temperatures to be moderately consistent over most of NSW,
SA and southern Tasmania (see background information). However, confidence levels are
weak to very weak in the southeast of SA, western Victoria and northern
Tasmania, so this outlook should be used with caution in those areas.
The outlook for winter mean minimum temperatures shows a 60 to 65%
chance of a seasonal average above the long-term median minimum temperature in northern
NSW. In remaining areas the probabilities are mostly in the 50 to 60%
History shows the oceans' effect on minimum temperatures in winter to be
moderately consistent over NSW and the northeast quarter of SA. However,
over western and southern SA, most of Victoria and Tasmania, the influence
is only weakly or very weakly consistent.