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Southeast Australia Struck by Anomalous Heat Wave

By: Christopher C. Burt, 7:15 PM GMT on March 15, 2013

Southeast Australia Struck by Anomalous Heat Wave

Southern Australia has endured an anomalous ‘Summer in March’ heat wave the first two weeks of this month akin to what the eastern two-thirds of the U.S. experienced in March 2012. Temperatures have averaged as much as 10°C (18°F) above normal.

The Australian Bureau of Meteorology released a special statement concerning this unusual heat event. The one statistic that seemed the most remarkable was that Melbourne, Victoria recorded 9 consecutive days (from March 4 to 12) when temperatures peaked at 30°C (86°F) or warmer (in fact all 9 days exceeded 32°C/89.6°F). This was the longest string of 30°C+ temperatures ever measured in the city for any month of the year since records began in 1855 (the previous record was 8 days on January 24-31, 1974). The nights were mild as well with 7 consecutive days (March 7-13) recording minimum temperatures of 20°C (68°F) or warmer, also an all-time record for such for any month. On the night of March 13th the minimum fell to only 26.5°C (79.7°F), the city’s warmest March night on record. Adelaide, South Australia experienced 10 consecutive days with highs above 32°C (89.6°F) from March 3 to March 12, the 2nd longest such streak in March on record (the longest was 15 days on March 3-17, 2008).

Departure from normal maximum temperature (top map) and minimum temperature (bottom map) for the period of March 1-12, 2013. Maps courtesy of the Australian Bureau of Meteorology.

The unusual heat was confined to the southern portions of Victoria, South Australia, and Tasmania. In spite of the long duration of the event few monthly record maximum temperatures were set although Bushy Park, Tasmania hit 37.4°C (99.3°F) on March 12th, just 0.6°C (1.1°F) short of the Tasmanian state monthly heat record of 38.0°C (100.4°F) set at Campania (Kincora) on March 14, 2008. Hobart hit 36.6°C (97.9°F), just shy of its March record of 37.3°C (99.1°F) set on March 13, 1940. The warmest temperature measured in Victoria was 40.4°C (104.7°F) at Mortlake Rececourse on March 11th and in South Australia 41.2°C (106.2°F) at Tarcoola Aero on March 12th. Both these figures are well short of March state monthly records.

The warmth can, in some way, be attributed to record high sea-surface temperatures (+0.5°C above normal), which have been observed all summer in the Australia region. Since February the sea-surface temperatures have become even more anomalous off the southern coast of Australia where they now stand some +3.0°C (5.4°F°) above normal. A strong and persistent high-pressure ridge has dominated the mid-latitudes of the southern hemisphere between Australia and New Zealand for the past several months contributing to the warm and dry weather. The North Island of New Zealand is currently experiencing an extreme drought.

Christopher C. Burt
Weather Historian

Extreme Weather Mini Blog Heat

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Very interesting blog but please Sydney is the capital of NSW Melbourne is in VICTORIA I know it's a big country but we are proud of Melbourne and do insist on it being placed geographically correct.
Yes it has been too hot but enjoying some rain today.
Quoting jansac:
Very interesting blog but please Sydney is the capital of NSW Melbourne is in VICTORIA I know it's a big country but we are proud of Melbourne and do insist on it being placed geographically correct.
Yes it has been too hot but enjoying some rain today.

Ouch and thanks for the correction. I've updated the blog to reflect the Victoria info.
This would probably be more analogous to a late September heat wave in the Northern Hemisphere. Its quibbling but the dynamics that drive fall heat waves and late Winter/early Spring heat waves are likely different. There is more kinetic energy in the flow in Spring and thus more ways for the atmosphere to act as a powered refrigerator extracting kinetic energy from the flow to heat warm areas and cool cold areas.
A possible analog is October 2007 in the eastern U.S.
(I lucked out for this and spent Columbus day weekend that year in Ocean City MD with wife and kids.. sometimes we win one)

The March 2012 warm spell was truly remarkable and I took a road trip to Jamestown NY from Washington DC for a kids hockey tournament on the ending weekend March 23-25. Seeing the NW PA landscape in bloom and greening this early was mind boggling as was standing in heat outside the arena in Jamestown and experiencing a lake breeze off lake Chautauqua(sp??) that knocked the temperature DOWN to 70F Friday, and driving through warm rain Saturday night and seeing frogs jumping all over the road.
in March!
in New York!

The closest analog I can remember to that warm spell was the last two weeks of Feburary and the first week of March 1976 in the eastern U.S.
Thanks for this data, another piece of the puzzle.
The blocking high over the Tasman Sea also brought drought to the north island of New Zealand this Summer and Autumn. It is the longest dry spell since 1919. Evidently Wellington, the capital of New Zealand located at the southern end of the north island, is reduced to a critically low drinking water supply, River water flows are at a record low levels. The city has banned outdoor watering and implemented water saving measures. TVNZ said that Wellington has '20 days of water left' in drought, and that was 5 days ago on 13 March. So, the weather pattern appears to have affected New Zealand as well as Australia.
Update: Here is the NIWA summary for New Zealand from 6th March: "Summer was characterised by much higher pressures than normal over the Tasman Sea and New Zealand region, with more southwesterly airflow than normal over the country. The frequent 'highs' over the country produced a very sunny summer for most of the country, and extremely dry conditions over most of the North Island. On 27 February, a state of drought was declared in Northland...."

Conditions are so bad that on 9 March "a near total fire ban was declared across the North Island, also for the first time." The effects of the drought have been estimated to cost about NZ$1 billion in lost agricultural production.
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