Dry start to summer across the country

Following a very wet start to spring across most key producing regions, the recently released climate outlook by the Bureau of Meteorology (BOM) suggests summer (December to February) rainfall will be below average for large parts of eastern Australia, while northwest WA will have a wetter than average three months.

The region with the least likelihood of exceeding the median rainfall for the outlook period covers most of NSW, southern Queensland and eastern Victoria. Conversely, in WA, the northernmost part of the Kimberley and the region surrounding Karratha (spanning up to Broome and down to Meekatharra), there is a 60-65% chance of above average rain from December to February.

This three month period falls within the northern Australian wet season, and the outlook is fairly neutral across the Top End and northern Queensland – in other words the probability of above or below average rainfall over summer is roughly equal. Central and south western parts of the country also have a neutral outlook for the three-months to February.

Looking at December alone, however, the chance of exceeding the median rainfall is low (up to 35%) across all of Australia. While the outlook is more positive in January for central and western areas of the country, rainfall across key producing regions in NSW and Queensland is likely to be below-average during the month. The southeast corner of Queensland and northeast NSW have a 20-25% chance of exceeding median rainfall in January. Northwest WA and south western SA have a 60-65% chance of above average rain for the month, while the remainder of the country is fairly neutral.

BOM report that the drier than average conditions forecast for December, particularly, are largely influenced by a northward shift in the normal position of the westerly winds to Australia’s south – known as the Southern Annular Mode.