The chances of increased daytime temperatures over summer (December to February)
are around 60 to 70% for Tasmania, Victoria, southern NSW and the agricultural
areas of South Australia (see map). This means for every ten years with ocean patterns like
the current, about six or seven would be expected to be warmer than average in
terms of daytime temperatures averaged over December to February, while three
or four would be expected to be cooler.
Across the rest of the southeastern region, the odds are between 50 and 60%,
which means roughly equal chances of warmer or cooler than normal conditions.
The pattern of seasonal maximum temperature odds across southeastern Australia
reflects a moderate to strong contribution from the Indian Ocean, where sea surface
temperatures in the central and southeastern Indian Ocean and especially off the
west coast of WA have recently been warmer than average. The equatorial Pacific is
generally still in a neutral state and not contributing significantly to the
temperature outlook for southeastern Australia.
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
over much of southeastern Australia. However, over southern NSW, central Victoria and much
of central and northern SA confidence is only weakly consistent, so this outlook needs to
be used with caution in these areas (see background information).
For most of southeastern Australia the outlook for overnight minimum temperatures
shows no significant shifts in the odds favouring either warmer or cooler than
normal conditions. In other words, the chances of minimums being warmer than
normal in most districts are about the same as the chances of being cooler (see
map). The only exception is the far northeast of NSW where there is a moderate
shift in the odds favouring warmer than normal minimum temperatures. In this
region the odds favouring above normal minimum temperatures are around 60%.
History shows the oceans' effect on minimum temperatures during summer to be moderately consistent
over northern NSW, northern SA and most of Tasmania. However, over the remainder of the southeastern
region, the effect is generally only weakly consistent, so this outlook needs to be used with caution
in these areas.