The pattern of seasonal temperature odds across SE Australia is a result of
continuing higher than average temperatures over much of the tropical Pacific Ocean,
and also in parts of the tropical and sub-tropical Indian Ocean. The Indian Ocean
has been warming strongly in recent months and this is the dominant influence
on the outlook.
Averaged over August to October, the chances are mainly between 60 and 75% for above-normal
maximum temperatures over SA, NSW, Victoria and much of Tasmania, with 75 to 80%
chances across the northern half of NSW (see map).
So in years with ocean patterns like the current, about six to eight August to
October periods out of every ten are expected to be warmer than average over
southeastern Australia, with about two to four out of ten being cooler.
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During August to October, history shows this
effect on maximum temperatures to be moderately consistent across most of
NSW, the northern half of SA and parts of Tasmania's north coast. In other areas
the effect is only weakly consistent (see background information).
Average seasonal minimum temperatures are also favoured to be warmer than normal across
mainland SE Australia (see map). The chances of increased overnight warmth (averaged
over the coming three months) are between 60 and 75% in Victoria, NSW and SA,
decreasing to between 55 and 60% in Tasmania.
History shows the oceans' effect on minimum temperatures over August to October to be
moderately consistent over much of NSW, SA and eastern Tasmania. Elsewhere, including most
Victoria, the effect is only weakly consistent.