The weekend's rain is a welcome change for many farmers in rural regions.
The weekend's rain is a welcome change for many farmers in rural regions. Matthew Purcell

Rainfall difficult to predict over autumn: BOM

THE Bureau of Meteorology's latest seasonal rainfall outlook leaves a lot to the imagination, leaving the country guessing what's in store for the coming months.

During autumn, there is near-equal chances of a wetter or drier three months across Australia.

The main climate drivers -- El Niño/La Niña and the Indian Ocean Dipole -- are neutral, which is why the rainfall outlook is not showing a tendency towards a wetter or drier than average three months ahead..

However, the Bureau's climate model suggests there is a chance El Niño will develop in autumn, which if so, would increase the chances of drier conditions in the south and east.

The chance of April to June rainfall being above median is close to 50 per cent across the country.

For the April to June period, past performance of the Bureau's model shows it has moderate accuracy across most of the country.

As for a longer term forecast for the Northern Rivers, there is a 75 per cent chance up to 200mm of rainfall will fall in Byron Bay and coastal areas during April, up to 100mm in Lismore and surrounds, and up to 50mm in parts further west.

Looking further ahead, there is a 75 per cent chance during April to June Byron Bay and Ballina could receive up to 600mm of rain, up to 300mm for towns around Lismore and Casino.

The median rainfall for Byron Bay and Ballina in this time is 490mm.

The outlook also suggests temperatures are likely to be warmer than usual when averaged over the next three months.

Rainfall this year

According to Weather Zone Lismore has received 343.6mm of rain this year (over 40 days), but the average rainfall to April is 605mm (over 64.3 days).

Byron Bay has been significantly less rainfall this year than usual, with just 192.4mm (over 38 days) compared to the average rainfall to April of 667.0mm (61.5 Days).

295.4mm of rain has fallen in Casino over 34 days this year, but that's still below the average 512.3mm (over 50.5 Days).