According to the latest climate statement issued by the Bureau of Meteorology's National Climate Centre, the last time there was widespread above average rainfall in NSW was in 2000.

"Since then we have had a succession of years generally below average, with two extremely dry years, 2002 and 2006, associated with El Niño events," manager of the Bureau's NSW Climate Services Centre, Perry Wiles, said.

"Autumn rain has been particularly affected, with eight consecutive autumns recording below to very much below average rainfall.

"This has been keenly felt in the south of the state where autumn rain is important for getting winter crops under way."

In the past three years, the Riverina and South West Slopes districts of NSW have been particularly hard hit, with rainfall very much below average, and some areas near the Australian Alps, from west of the ACT south into Victoria, are now at the lowest level ever recorded on the three year time scale.

These areas are critical as they generally account for a substantial proportion of the inflows into the Murray-Darling river system.

"The story for NSW is not all bad, however," Mr Wiles said.

"While there are few signs that the drought in the south is letting up, the situation has eased in the north east of NSW.

"The northern half of the Murray-Darling Basin has had near- to above-average rain in the last 12 months, especially last summer associated with the La Niña event in the Pacific Ocean from late 2007 into early 2008."

As for the immediate outlook, Mr Wiles said the next three months were expected to favour "continued easing of conditions in the north of the state with the odds about 60pc of receiving above median rainfall".

"But unfortunately these odds drop off as you move south so we are not expecting much relief in those parts," he said.