(AU) BOM Says Australia Just Had Its Hottest November On Record

 ABC Weather - Kate Doyle

It has been a hot few months across the country. (ABC News: Mary Lloyd)

Key points Australia has just broken the record for its warmest November on record It was also our warmest spring for minimum and mean temperatures Spring's rainfall was well below the records but significantly greater than last year

The Bureau of Meteorology (BOM) has just finished crunching last month's numbers and confirmed it was Australia's hottest November on record for maximum, minimum and mean temperatures.

 It was also the country's hottest spring on record for mean and minimum temperatures.

November's maximums came in at 2.9C above the 1961-90 average, surpassing the 2.4C mark set in November 2014. 

The national minimums were at 2.04C above the average and means at 2.47C.

It wasn't just the past few days that were hot — spring overall saw Australia's mean and minimum temperatures reach the warmest on record at 2.03C and 1.91C above the average, respectively.

Spring's maximum temperatures were only the fifth warmest on record at 2.15C above the 1961-90 average.

Rainfall near average for spring

 Nationally, spring rainfall was 8 per cent below average and close to average for most of the country, according to BOM senior climatologist Blair Trewin.

But parts of eastern Queensland, north-east New South Wales and western Tasmania were drier than average.

Spring rainfall was just below average for the nation as a whole in spring. (Supplied: Bureau of Meteorology)

Outback South Australia and far south-west New South Wales, however, had above-average rainfall.

November was particularly dry for the eastern states but wet in the west.

Many regions are still in drought, while for others this year has been a real turnaround.

Good winter rain in the south means farmers are on track to produce the second biggest grain crop ever, according the latest update from the Australian Bureau of Agricultural Resource Economics and Sciences (ABARES).

The dry window over the past few weeks has been exactly what many farmers needed to get their crop out.


BOM summer 2020-21 climate and water outlook. Youtube 

How could it be hotter than last year?

Last spring was extremely dry, the driest on record.

Australia went through it's highest mean temperature average in over 100 years of records. (Supplied: Bureau of Meteorology)

Dr Trewin said when it was extremely dry, there were very hot days but also very cool nights.

So we may remember the hot spring days last year — which were definitely hotter than this year — but last year's cool nights drew the average down.

"This year the real standout has been the warm nights," Dr Trewin said.

Australia's spring mean temperature anomaly 
1910 to 2020 relative to the 1961 to 1990 average of 22.5C

Chart: ABC Weather: Kate Doyle.  Source: Bureau of Meteorology Get the data

Beyond the extremely dry conditions, one contributor to last year's fires was the strongly negative Southern Annular Mode (SAM). 

SAM's westerlies brought hot air from central Australia down over the east coast and contributed to the horror fire weather.

A year later, the SAM has been in neutral, making these extreme conditions less likely.


How to prepare for a heatwave | Emergency Tips. Youtube 

Wasn't La Niña going to make things wet and cool?

Dr Trewin said the climate driver was still there but the rainfall was taking its time to arrive.

He said while some La Niña years like 2010 brought heavy rain early, other years took longer to have their effect on Australia.

This year was looking a bit like 1988, Dr Trewin said — 1988 had a strong La Niña but also had a very hot spring before the rain kicked in, making for an extremely wet first half of 1989.

"We still have a pretty high level of confidence we're going to have a period of sustained above-average rainfall for the coming months."

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Spring was also expected to be wetter than average, but short-term climate drivers have gotten in the way in recent weeks and prevented the La Niña from bringing about the expected wetter conditions.

Then there is the climate influence.

April-to-October rainfall has been on a downward trend over southern Australia for the past few decades.

Australia's climate has also warmed on average 1.44C (plus or minus 0.24C) since 1910, as outlined in the most recent BOM and CSIRO State of the Climate report.


How to prepare for a flood | Emergency Tips. Youtube 

What's on the cards this summer?

The outlook for the coming months indicates temperatures could be below average in the centre and above-average rainfall is likely for most of the country, but of course it doesn't count until it hits the ground.

Daytime temperatures are expected to be average to below average, but overnight temperatures are expected to remain high. (Supplied: BOM)

Links

• AU) Australia Endures Hottest Spring Ever, With Temperatures More Than 2C Above Average 
• The heatwave that was: SA and NSW November temperature records fall
• Farmers rejoice as this year's grain harvest is tipped to set records
• New emergency warning system rolled out across Australia
• Short-term climate drivers are fighting back the rain, but BOM's outlook suggests they won't be able to hold out much longer
• Rising levels of carbon dioxide increasing extreme weather events in Australia, report finds
• Bushfire threatens Sydney homes after city swelters through hottest November night on record
• (AU) Bureau Of Meteorology Says The NT Experienced Its Hottest November In 100 Years
• Sydney Records Hottest November Night As Heatwave Sweeps City
• Rising Temperatures Will Cause More Deaths Than All Infectious Diseases – Study
• (AU) Trend Towards Worsening Heatwaves Is Accelerating, New Research Finds
• (AU) Just How Hot Will It Get This Century? Latest Climate Models Suggest It Could Be Worse Than We Thought