"Some good rainfall during December last year has had little effect on the overall pattern of rainfall deficiencies," the bureau said on Monday.

Central western NSW was least affected by drought in January, with rainfall close to average.

But parts of the northern tablelands, northern rivers, mid-north coast and Hunter districts had January totals below to very much below average, the bureau said.

The rainfall deficit pattern in the three months to January showed the central part of the state had very much below average rainfall conditions, while the remainder of the state was mostly below average, it said.

The state also experienced above average monthly mean maximum temperatures in January, the bureau said.

The greatest departures from normal occurred in the northwest of the state, with temperature anomalies of up to five degrees Celsius, it said.

Australia's drought, which began in March 2002, has devastated crops and livestock and generated serious bushfires in eastern parts of the country.

The drought is attributed to an El Nino weather condition, caused by abnormal sea surface temperatures in the Pacific. The weather bureau believes the El Nino is most likely to begin to break up in coming months.

This is one of the worst droughts in Australian recorded history.