Australia is expected to receive above average rainfall this month before a return to typical January conditions, the Bureau of Meteorology says in a summer climate outlook.

The likelihood of above average falls has increased in recent weeks compared with earlier forecasts, raising the risk of riverine and flash flooding in parts of eastern, western and northern Australia, climatologist Caitlin Minney says.

“Warmer than average sea surface areas are forecast across much of the globe, including in waters around Australia,” she says. “Warm oceans enhance atmospheric moisture and energy, which can increase the severity of storms and enhance rainfall.”

The bureau also expects summer to be warmer than average across most of the country, and fire agencies forecast an increased bushfire risk in parts of Victoria, NSW, WA, SA and the NT.

“There is an increased chance of unusually high maximum temperatures across Tasmania and western WA, and parts of southeastern SA and western Victoria, with up to 3.5 times the normal chance,” the outlook says.

A La Nina watch remains in place, but if an event develops in the Pacific it is forecast to be relatively weak and short-lived.

The Indian Ocean Dipole index has been below the negative threshold since mid-October, nearing the period required for an event to be declared, but all but one of the models monitored by the bureau indicate it will return to neutral levels this month.

A La Nina event and negative Indian Ocean Dipole are typically associated with wetter weather in parts of Australia.