The pattern of seasonal rainfall odds across Australia is mainly a result of warm conditions in the Indian Ocean in January and March.

The Pacific Ocean has had little contribution to this forecast.

For the May to July period, the chance of exceeding median rainfall is between 60-70pc in a region covering the northeast half of NSW and most of southern Queensland (see map).

In addition, parts of the NT and WA also have 60-65pc chances of a wetter than normal three months, although some of this region is seasonally dry at this time of year.

This means that for every 10 years with ocean patterns like the current, about six or seven years are expected to be wetter than average over these parts in the north and east, while about three or four years are expected to be drier.

Across the rest of the country, the chance of exceeding the median rainfall during the coming three months is between 40-60pc, meaning that above average falls are about as equally likely as below average falls in these regions.

Outlook confidence is related to how consistently the Pacific and Indian Oceans affect Australian rainfall.

Pacific climate patterns are currently neutral and the consensus from computer models is for near average tropical Pacific surface temperatures in the middle of the year, although with some warming from present values.

The SOI is an encouraging +8 for the 30 days ending 21 April, but autumn SOIs are often unreliable and the positive trend won't be set in concrete until later in the year.