The pattern of seasonal temperature odds across southern Australia is mostly a result of
continuing higher than average temperatures over parts of the
tropical and sub-tropical Indian Ocean. The La Niña pattern of cooler than
average temperatures in the central to
eastern equatorial Pacific has contributed to the increased chances of cooler
than average daytime temperatures in southern Queensland and northern NSW.
Averaged over summer, the chances are between 60 and 70%
for above-normal maximum temperatures over Tasmania, Victoria, southern NSW and
southern South Australia (see map).
So for every ten years with ocean patterns like the current, about six or seven
summers are expected to be warmer than average over
southeastern Australia, with about three or four being cooler.
Contrasting this, in much of southern Queensland, stretching into northeast NSW,
the chances of getting cooler than normal maximum temperatures averaged over
summer are 60 to 70% (i.e. 30 to 40% chance of higher than normal).
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During summer, history shows this effect on
maximum temperatures to be moderately consistent across much of the eastern half
of the country and parts of northwest and southern WA, but generally weakly or
very weakly consistent elsewhere (see background information).
Minimum temperatures for the summer are favoured to be warmer than normal across
southwestern and northeastern Australia (see map). The chances of increased
overnight warmth (averaged over the coming three months) over much of the
southern half of WA are greater than 60%, reaching above 80% over a large area.
Cape York Peninsula in Queensland has values in the 60 to 65% range, while
the chances in remaining parts of the country are in the 40 to 60% range.
History shows the oceans' effect on minimum temperatures during summer
to be moderately consistent over much of the country, with the exception of
southeast Australia and southern SA.