Consistent with Tuesday's La Nia declaration, the Bureau of Meteorology's Summer Outlook shows eastern Australia is likely to be wetter than average, with an increased risk of tropical cyclones, heavy rainfall and widespread flooding.

However, this does not mean we can relax when it comes to bushfires.

The BOM says the bushfire risk may not be as high this summer as in some recent years, but bushfires happen every summer in Australia and even short periods of hot and windy weather will raise the fire risk.

"This year we need to be extra careful about grass and crop fires, particularly across inland areas and in the southwest of the country where we have had good growth over winter and spring," Bureau's Head of Operational Climate Services, Dr Andrew Watkins said.

He added flood alerts were high.

"Spring has been wetter than normal and, as a result, soil moisture is high, water storages are full, and we've seen flooding in some areas.

Any additional rain on our already wet landscape will increase the flood risk for eastern Australia this summer."

The BOM says summer days are likely to be warmer than average across most of Australia, except in the south-east.

Minimum temperatures are likely to be above average across most of the country, so we're in for some warmer nights.

"The risk of heatwave is about average this year, and it's important to remember that heatwaves are Australia's most deadly natural hazard. Warm nights after hot days in particular make heat stress a significant health risk," Dr Watkins said.