The pattern of seasonal temperature odds across Australia is due to higher
than average temperatures in both the Pacific and Indian Oceans, with the effect
from the Pacific being dominant.
Averaged over the coming three months, the chances are mainly between 60 and
80% for higher than normal maximum temperatures northeast of a line from Derby
in northwest WA to Sydney. Within this region, the chances peak above 80%
in eastern Arnhem Land and in an area of north Queensland surrounding the east
coast of the Gulf of Carpentaria (see map).
So in years with ocean patterns like the current, about six to eight February to
April periods out of every ten are expected to be hotter than average in these
parts of northern and eastern Australia, with about two to four out of ten being cooler.
Contrasting this, there are 60 to 65% chances (i.e. 35 to 40% chances of higher
than average) for a cooler than normal February to April period in a band stretching
from the interior of WA, across western and southern SA to central Victoria. A few
patches across Tasmania also have similar probabilities.
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During the February to April period, history
shows this effect on maximum temperatures to be moderately consistent
over Queensland, the northern NT, central WA and patches in SA, Victoria, NSW and
Tasmania. In western WA and in a band from the southern NT to most of NSW, the
effect is only weak or very weak (see background information).
The chances of seasonal minimum temperatures being higher than the median are
between 60 and 80% over most of the northern tropics, indicating
a moderate to strong shift in the odds towards warmer than normal conditions.
In contrast, cooler than average nights (i.e. a 30 to 40% chance for warmer than normal)
are favoured in the southeast of the mainland.
History shows the oceans' effect on minimum temperatures during the February to April period
to be moderately consistent over large parts of the country.