Recent climate
July rainfall in the SWLD was generally near average, however May and June were dominated by high pressures and clear skies, which meant the May to July total rainfall was very much below average throughout the SWLD. For southwest Western Australia, this year’s April to June period was the driest from records back to 1900. Outlooks for this period from both the SSF and from the Bureau were for below average rainfall (see the May edition of the Seasonal Climate outlook).
In July, the SWLD maximum and minimum temperatures were near average to above average, however the dry outlooks suggest the potential for clear night skies means a greater risk of frost in many areas
In July the atmospheric pressure was lower than normal over the southwest, as a result of a series of cold fronts.
Cooler than normal Indian Ocean sea surface temperatures northwest of Western Australia have reduced cloudband development and therefore rainfall to the south-west and wheatbelt.
The El Niño-Southern Oscillation (ENSO) remains neutral. All climate models surveyed by the Bureau indicate the tropical Pacific Ocean is likely to stay ENSO-neutral for the rest of 2017.
The Indian Ocean Dipole (IOD) is neutral. Two of six international climate models suggest positive IOD thresholds could be reached in the coming months but only one model maintains these values long enough to be considered a positive IOD event. See the Bureau of Meteorology’s IOD and Pacific Ocean interaction for details.
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 near zero.
The table below gives a summary of past month and three month southwest 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 | Below average |
| SWWA mean Temperature | Average to above average | Above average |
| SWWA atmospheric pressure | Low | High |
| Indian Ocean Sea surface temperature | Cooler | Cooler |
| El Niño/Southern Oscillation (ENSO) | Neutral | Neutral |
| Indian Ocean Dipole (IOD) | Neutral | Neutral |
| Southern Annular Mode (SAM) | Positive | Positive |