The Bureau of Meteorology’s outlook for December predicts temperatures will be, on average, a few degrees lower than normal across Tasmania.

The state joins southern Western Australia in enjoying a more moderate summer while the north-east and western mainland can expect to swelter through a high pressure system. 

Bureau of Meteorology climatologist Ian Barnes Keoghan said that generally speaking Tasmania can expect fewer hot days this summer than last.

“For most of Australia, especially for eastern Australia, the outlook is favouring dry weather,” he said.

“But that is not the case for Tasmania, where the outcome is more likely a cooler than average December and a wetter than average.”

While rainfall predictions are less certain, Mr Barnes Keoghan said that there was a slight chance the south-west of the state would experience more rainfall, with temperatures averaging a degree or two lower.

Mr Barnes Keoghan said that the predictions for a cooler summer stem from a lack of influence from the two largest global-scale climate drivers that influence Tasmania: El Nino sitting over the Pacific Ocean, and the Indian Ocean Dipole.

“[The El Nino] has been wanting to go toward a La Nina which would favour wetter conditions, but it hasn’t quite got there,” Mr Barnes Keoghan said.

“Meanwhile … the influence of the Indian Ocean Dipole has weakened, which we normally see at this time of year.

“So we’re sort of left without those big two doing much.”

Instead, Mr Barnes Keoghan said the primary weather influence across Tasmania remains the Southern Annular Mode (SAM), which is expected to stay in a negative phase and will push a belt of westerly winds north.

“For most of Australia, that actually means it will be warm and dry,” Mr Barnes Keoghan said.

“But for Tasmania, especially for the western part of the state, it tends to be cooler and wetter.”

He said the westerly winds pushed by the SAM are common throughout Tasmania in winter and spring, but Tasmanians can expect the winds to linger further into summer this year, keeping temperatures down.