Rainfall deficiencies have increased across parts of southeastern Australia following the country's third driest May on record.

The start of 2018 has been notably dry across much of Australia's southeast inland. Despite being almost halfway through the year, much of southwest Queensland, western NSW, northwest Victoria and the eastern half of SA has received less than 20 per cent of their annual average rainfall totals so far during 2018.

This dry spell is made even more remarkable by the fact that it has occured in the absence of El Nino - a Pacific Ocean-based climate pattern that often causes below average rainfall in eastern Australia.

In an updated drought statement issued by the Bureau of Meteorology on Monday, it is evident that the dry start to 2018 has caused long-term rainfall deficiencies to increase across parts of South Australia, NSW and southern Queensland. Severe rainfall deficiencies are now widespread in these three states.

Outback areas of western NSW and northern SA have seen the most significant absence of rainfall so far this year, with some pockets receiving little if any rainfall so far during 2018.

Broken Hill's running annual rainfall total of 12mm as of 9am on Monday 4th June is their lowest to this point in the year since records commenced back in 1889. Put another way, this is Broken Hill's driest start to a year in more than 120 years of records.

Unfortunately, the latest climate outlook issued by the Bureau of Meteorology indicates that the run of below average rainfall is likely to continue during winter across Australia's southeast mainland, including NSW, Victoria, southern Queensland and South Australia.