The pattern of seasonal temperature odds across southeast Australia is mostly a
result of warm conditions in the Indian Ocean in January and March, with the
Pacific Ocean having very little effect at all.
The chances of exceeding the median maximum temperature for the May to
July period are around 50 to 60% for all of SE Australia. This means
that for every ten years with ocean patterns like the current, about
five or six years would be expected to be warmer than average,
while four or five would be expected to be cooler.
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During the May to July period,
history shows this effect on maximum temperatures to be strongly
consistent over Tasmania, the southeast districts of SA and most of
Victoria, and moderate over the rest of the southern half of SA, and
over southern and inland NSW, apart from the northwest (see background information).
However, confidence levels are low in northern SA and in the northwest of
NSW, and along the coast and adjacent ranges north from Sydney, so this
outlook should be used with caution in those areas.
The outlook for May to July mean minima shows a 60 to 70%
chance for higher than normal seasonal average temperatures
in northern NSW. So for every ten years with ocean
patterns like the current, about six or seven May to July periods are likely
to be warmer than normal over this part of southeastern Australia, with
about three or four being cooler.
History shows the oceans' effect on minimum temperatures in the May to July
period to be moderately to strongly consistent over northern and
especially northeastern NSW, and moderately consistent over the remainder of
NSW (apart from the southwest), Tasmania and in patches along the coast
of both Victoria and SA. Elsewhere the effect is only weakly or very