Seasonal Climate Outlook

Recent climate

January rainfall was below average to average. January maximum temperatures were average to above average, below average for South Coastal and South East Coastal forecast districts. Minimum temperatures were below average to average. Since 1 January, Koorda has had 37.8 mm of rain from isolated thunderstorms. 

Rainfall to date map 1 January to 5 February 2023, showing rainfall for Central West and Central wheatbelt forecast districts.
Rainfall to date map 1 January to 5 February 2023 of the South West Land Division.

In January the atmospheric pressure was near normal over the SWLD.

Sea surface temperatures are now average in northern Australia. The sea surface temperature outlook for February to March by the Bureau of Meteorology indicates SSTs will be normal to warm around Western Australia. Warmer temperatures marginally increase the likelihood of tropical cyclones developing.

The Indian Ocean Dipole (IOD) is neutral and has little influence on Australian climate while the monsoon trough is in the southern hemisphere (typically December to April). Two models (including the Bureau of Meteorology) are indicating the development of a positive IOD in June.

The Southern Annular Mode (SAM), also known as the Antarctic Oscillation (AAO), describes the north–south movement of the westerly wind belt that circles Antarctica, dominating the middle to higher latitudes of the southern hemisphere. The Southern Annular Mode (SAM) is currently positive and is likely to be positive until at least mid-March.  SAM has no influence on rainfall in the SWLD in summer.  For more information see the Bureau of Meteorology’s Climate Driver Update.

The La Niña continues in the tropical Pacific. ENSO events typically peak in late (southern hemisphere) summer and decay during the autumn; current outlooks indicate this La Niña may decay slightly earlier than usual (February). The Bureau of Meteorology is indicating an El Niño developing in June. However, as accuracy is generally lower for long-range ENSO forecasts made during summer, ENSO outlooks that extend past autumn should be viewed with caution.

An El Nino together with a positive IOD, would mean reduced rainfall for the South West Land Division, as seen in the map below. Although, skill for these forecasts are currently poor, but are worth watching out for as the year progresses.

Winter-spring mean rainfall deciles for 7 seasons which where El Niño and positive Indian Ocean Dipole. Rainfall deciles for South West Land Division was decile 4 and below.
Winter-spring mean rainfall deciles for 7 seasons which where El Niño and positive Indian Ocean Dipole

The table below gives a summary of past month and three-month South West Land Division (SWLD) climate conditions, and can indicate what is likely to occur in the near future if climate conditions follow the current pattern.

Climate Indicator Past month Past 3 months
SWLD Rainfall Average to below average Mixed
SWLD Mean Temperature Mixed Below average to average
SWLD atmospheric pressure Normal Below normal
Indian Ocean Sea surface temperature Warmer Warmer
El Niño/Southern Oscillation (ENSO) La Niña La Niña
Indian Ocean Dipole (IOD) Neutral Neutral
Southern Annular Mode (SAM) Positive Positive