The pattern of seasonal maximum temperature odds across southern Australia is a result of
the La Niña pattern of cooler than average temperatures along the
equatorial Pacific. In northeast Australia, effects from the Indian and Pacific
Oceans cancel each other: below-normal temperatures are promoted by the
La Niña pattern, while above-normal temperatures are promoted by continuing
higher than average temperatures in the central to southeastern Indian Ocean.
Averaged over January to March, the chances are above 60% for above-normal maximum
temperatures over southern WA, most of SA, Tasmania, Victoria, and the southwest
half of NSW (see map). Over much of Victoria and southeast SA the chances are in
the 75 to 80% range.
So for every ten years with ocean patterns like the current, about six to eight
March quarters are expected to be warmer than average over these parts of
southern Australia, with about two to four being cooler.
Outlook confidence is related to how consistently the Pacific and Indian
Oceans affect Australian temperatures. During the March quarter, history
shows the effect on maximum temperatures to be moderately consistent over
large areas of the country. The effect is weak or very weak in parts of
northern, central and far western Australia (see background information).
Minimum temperatures for the March quarter are favoured to be warmer than normal across
much of northern and western Australia (see map). The chances of increased
overnight warmth (averaged over the coming three months) are mainly between 60
and 70% in these areas. Across the rest of the country, the chances of the
seasonal mean minimum being above the long-term average are between 40 and 60%.
History shows the oceans' effect on minimum temperatures during the March quarter
to be moderately consistent over most of Queensland, the NT and northern WA.
Elsewhere the effect shows weak to very weak consistency.