The pattern of seasonal maximum temperature odds across southeastern Australia
is a result of the combined effects of above average temperatures
in the Indian Ocean immediately to the west of Australia and cooler than average
waters in the central to western equatorial Pacific in association with the decaying
La Niña pattern.
Averaged over winter the chances for above-normal maximum temperatures are
close to 50% over the entire southeast Australia (see map). Very weak shifts
in the odds are seen towards warmer maximum temperatures in Victoria and
southeast SA and towards cooler temperatures in far northern NSW. However,
in years with ocean temperature patterns similar to those currently observed,
warmer-than-normal daytime winter temperatures are observed as often as
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 the region (see background information).
There is no shift in the odds towards above-normal or below-normal minimum
winter temperatures in southeastern Australia (see map). So for every ten
years with ocean patterns like the current, night-time temperatures in about
five winter periods are expected to be warmer than average and about five
are expected to be cooler than average.
History shows the oceans' effect on minimum temperatures in winter to be
moderately consistent over NSW and most of SA, but over Victoria, Tasmania
and parts of southeast SA the influence is only weakly or very weakly consistent.