The pattern of seasonal maximum temperature odds across Western Australia is a result of
the combined effects from above average temperatures in the Indian Ocean
and cooler than average temperatures in the equatorial Pacific (La Niña).
Averaged over May to July, the chances are between 35 and 40% for above-normal
maximum temperatures in much of the Kimberley extending into the far east of the
Interior district (see map). So for every ten years with ocean patterns like
the current, about six May to July periods are expected to be cooler
than average over these parts of the State, with about four being warmer.
Over the rest of WA, the chances of exceeding the three-month median maximum
temperature are mainly between 40 and 45%. So the chances of being cooler than normal are
about the same as the chances of being warmer.
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 moderately consistent over most of Western
Australia, with the exception of the far eastern interior near the NT and SA borders
(see background information).
The outlook for seasonal minimum temperatures is also mainly neutral. Averaged over the
May to July period, the chances of overnight temperatures being above the long-term
normal range from 40 to 45% in the south to 55 to 60% in the north (see map).
History shows the oceans' effect on minimum temperatures in the May to July period
to be moderately consistent over large patches in WA.