Welcome to the Climate and Water Outlook for August to October 2017.
Winter so far in southern Australia has been notably cold and dry.
But northern Australia has had record warm temperatures and some early bushfires.
Outlooks suggest dry and warm conditions are likely as we head into spring.
But first, let's look at recent conditions.
Australia had its second driest June in 118 years of records, and July has stayed drier
than average over much of the south.
For southwest Western Australia, this year’s April to June period was the driest on record.
Rainfall deficiencies since April are at ‘serious’ to ‘severe’ levels in key agricultural
areas of WA, the Eyre Peninsula in South Australia, eastern Victoria, western Tasmania and central
New South Wales.
Colder-than-average nights and early morning frosts have been widespread across the south.
In contrast, very warm temperatures have persisted across the tropical north, setting records
for this time of the year in some parts.
Clear skies and dry, warm air have led to unusually high evaporation rates in many areas.
Evaporation was greater than rainfall over large parts of southeastern Australia in June,
which is quite unusual for winter.
This means soil moisture has continued to fall in many areas, and is now below average
in most parts of southern Australia.
Low rainfall, high evaporation and dry soils have meant a late start to the winter filling
season for southern water storages.
Normally we’d expect to see a noticeable increase in water levels from June to July.
So what's driving Australia’s climate towards drier and warmer conditions?
Our main climate drivers—ENSO and the Indian Ocean Dipole—are idling in neutral at the
moment, and both are likely to stay that way until the end of the year.
However, high pressure systems are likely to persist just south of Australia as we head into spring.
This typically means sunnier days and less rain for southern parts, and higher temperatures for the north.
The persistent high pressure over the last two months may be related to very warm sea
surface temperatures across both the Pacific and Indian oceans.
So what’s the rainfall outlook for August to October?
While El Niño is now unlikely, below-average rainfall is still expected for parts of southern Australia.
August in particular is likely to bring a dry end to winter.
In terms of temperatures: Days and nights are likely to be warmer than average for much
of Australia, but the potential for clear night skies means a greater risk of frost
in many areas.
Turning to streamflows for July to September: Low flows are more likely at most sites, mainly
along the east coast and in the south.
Near-median and high flows are expected at locations in the northwest, as water from
bumper wet-season rains travels through the landscape.
It's now fire season in the north.
The bumper wet season rains also led to lots of vegetation growth.
Record-warm temperatures have dried this out rapidly, and fires have already occurred south of Darwin.
The northern Australia seasonal bushfire outlook shows several areas with above-normal fire potential.
More details are available on the Bushfire and Natural Hazards CRC website.
In summary: high pressures continue to dominate southern Australia;
temperatures are likely to be warmer than average;
rainfall is likely to be below average for southern Australia; and
streamflows are expected to be low at most locations.
For more details, visit our website at bom.gov.au/climate/ahead.
You can also get updates via Facebook and Twitter.
Our next end-of-month video will be released on Thursday 31 August.
For the Bureau of Meteorology, I’m Andrew Watkins.