Western Australian temperature outlook

Issued 18 December 2013

Warmer season most likely for much of the Kimberley

Text details of chance of warmer maximum and minimum temperatures

Summary

  • Warmer days and nights are most likely over much of the Kimberley.
  • Cooler days are most likely in southwest WA
  • Climate influences include a neutral tropical Pacific, and a warm Indian Ocean
  • Outlook accuracy for maximum temperatures is moderate over most of WA, with minimum temperature accuracy moderate across northern WA with patches of lower accuracy in the southern half of the State; see accuracy tab for more detail.
Probability of exceeding median maximum temperature, larger view Probability of exceeding median minimum temperature, larger view

Details

The chances of the January to March maximum temperature exceeding the long-term median are greater than 60% over the north and east Kimberley (see map). Odds increase to greater than 70% over the far north Kimberley. So for every ten January to March outlooks with similar odds to these, about six or seven of them would be expected to be warmer than average over these areas, while about three or four years would be cooler.

Conversely, the chances of exceeding the median maximum temperature is less than 40% over southwest WA, whilst the chances of receiving a cooler or warmer than normal January to March is roughly equal (i.e., close to 50%) over the remainder of the State.

The chances that the average minimum temperature for January to March will exceed the long-term median are greater than 60% over much of the Kimberley, and parts of the west Pilbara. Odds increase to greater than 70% over the far north Kimberley.

Across most of WA, the chances of receiving a cooler or warmer than normal January to March in terms of minimum temperatures is roughly equal (i.e., close to 50%).

Climate influences

The El Niño-Southern Oscillation (ENSO) remains neutral, with the majority of atmospheric and oceanic indicators close to their long-term average. Dynamical models surveyed by the Bureau suggest ENSO-neutral conditions are likely to persist at least for the austral summer and early autumn. This means there is no strong shift in the odds from the tropical Pacific in this outlook.

Although the Indian Ocean Dipole has limited impact upon Australia during the months from December to April, the broad area of warmer than average sea surface temperatures across the central Indian Ocean has been shown to influence the climate over large parts of Australia at this time of year.

Lower surface pressures are likely to bring cooler and potentially wetter conditions to parts of southern Australia (such as Tasmania and parts of southwest WA) early in the outlook period. For northern regions, tropical Australian sea surface temperatures are currently average to slightly cooler than average, and are expected to remain that way over the forecast period. Weak to moderate tropical activity (cloud and rainfall associated with the Madden-Julian Oscillation) is expected in the first month.

How accurate is the outlook?

Maximum temperature outlook accuracy for the January to March period is:

  • Moderate western and northern parts of WA
  • Weak over southern parts of the State

Minimum temperature outlook accuracy for the January to March period is:

  • Moderate over the northern half of WA, and western and southern coastal parts
  • Weak through the much of the southern half of WA