Recent climate
Rainfall in March was average to above average for most of the South West Land Division. The last three months, January to March was very much above average, both the Bureau and DAFWA outlooks saw probabilities close to 50% for this period and so offered little guidance (See January edition of the Seasonal Climate outlook). Check DAFWA rainfall to date tool and DAFWA soil water tool for rainfall totals and modelled stored soil moisture estimates.
March South West Land Division maximum temperatures were below average (decile 2-3), whilst minimum temperatures were near average.
The far eastern Pacific Ocean has warmed substantially, with temperatures now more than three degrees above average. While this is unlikely to be affecting Australia’s climate right now, models suggest this local warming will spread across more of the tropical Pacific. The Bureau of Meteorology’s ENSO Outlook has moved to El Niño WATCH, as seven of eight climate models we survey suggest El Niño during winter. An El Niño typically biases Australia's climate towards a drier than average winter-spring (for eastern Australia), and warmer daytime temperatures in the south.
The Indian Ocean Dipole (IOD) remains neutral. The IOD has little influence on Australia from December to April. Five out of six models are indicating a positive IOD by August, which means a greater likelihood of reduced rainfall for the SWLD in winter and spring. In the past, a positive IOD combined with an El Nino has meant reduced rainfall for winter and spring for SWWA. See the Bureau of Meteorology’s IOD and Pacific Ocean interaction for details.
Indian Ocean sea surface temperatures (SSTs) north and west of Australia have cooled in the past month and now are below average. This means that heavy rainfall events from cold fronts are less likely as there is less warmth in the ocean to the west and a weaker north/south temperature gradient. For a summary of Pacific and Indian Ocean outlooks, see the Climate Model Summary produced by the Bureau.
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. SAM is currently positive and is expected to remain so through April. A positive SAM in autumn can mean drier conditions for the south-west corner though has a limited impact on the Wheatbelt.
In March the atmospheric pressure was lower than normal over the south-west. The mean sea level pressure is forecast to be higher in the coming months, meaning fewer cold fronts are likely to cross the coast.
The table below gives a summary of past month and three month south-west Western Australia (SWWA) climate conditions, and can be used as an indication of what is likely to occur in the near future, if climate conditions follow the current pattern.
| Climate Indicator | Past month | Past three months |
|---|---|---|
| SWWA rainfall | Average to above average | Above average |
| SWWA mean temperature | Average to below average | Below average |
| SWWA atmospheric pressure | Lower to normal | Normal |
| Indian Ocean sea surface temperature | Cooler | Cooler |
| El Nino/Southern Oscillation (ENSO) | Neutral | Neutral |
| Indian Ocean Dipole (IOD) | Neutral | Neutral |
| Southern Annular Mode (SAM) | Positive | Negative |