The Summer of 2009/2010
Rainfall
Overall comments:
Rainfall this summer was above average across most of central and eastern Australia, particularly over western NSW, western QLD, northern SA and the southern parts of the NT. The above average falls were mainly the result of the southern movement of the monsoon through January and the inland path taken by both Tropical Cyclone Lawrence in late December and Tropical Cyclone Olga in early February. This pattern brought above average rain to Darwin, Brisbane, Sydney and Canberra.
The heavy rains from these tropical weather systems failed to reach the southern coastline with below average rain falling in Melbourne, Hobart and Adelaide. Adelaide recorded only 33mm, its driest summer since 1998/1999.
Rain was well below average through most of WA and was the lowest on record for parts of the southwest. Perth only received 0.2mm of rain which makes the 2009/2010 summer its driest on record. The below average rain in the west was partly due to the absence of tropical cyclones in the region.
Capital cities rainfall summary:
Brisbane
December 172.2mm, January 40.2mm, February 262mm
Total 474.4mm
Average 451.2mm (old site)
Sydney
December 66.8mm, January 36mm, February 239.2mm
Total 342mm
Average 297.2mm
Canberra
December 76mm, January 7.8mm, February 125.4mm
Total 209.2mm
Average 167.7mm
Wettest since 2007/08 if <209.4
Melbourne
December 60.2mm, January 25.6mm, February 57.8mm
Total 143.6mm
Average 153.9mm
Wettest since 2005/06
Hobart
December 58.6mm, January 14.4mm, February 34.2mm
Total 107.2mm
Average 144.6mm
Driest since 2002/03
Adelaide
December 18.2mm, January 9.6mm, February 5.6mm
Total 33.4mm
Average 59.9mm
Driest since 1998/99
Perth
December 0mm, January 0mm, February 0.2mm
Total 0.2mm
Average 35mm (old site)
Driest on record
Darwin
December 457.2mm, January 630.2mm, February 277.6mm
Total 1365.0mm
Average 1038.3mm
Temperature
Overall comments:
It was hot summer for much of the nation, with every capital city seeing above average minimum and maximum temperatures.
Additionally, Melbourne may see its 3rd or 4th hottest summer on record (combining mins and maxs). This was partly due to humid and warm conditions through the first half of February that pushed the average minimum temps 3.5 degrees above the long term average. Max temps were also 2.8 above average in Feb, Once again, I'll put together a draft release for you today.
High humidity levels over eastern Australia created very warm nights in Sydney, Canberra and Melbourne. Sydney’s average summer minimum temperature was in the top 3 for the past 150 years of records. Melbourne and Canberra’s average summer temperatures (combined minimums and maximums) were more than 2 degrees above the long-term average, while Hobart and Adelaide were both around 1.5 degrees above the average.
Perth was also a stand-out for heat through summer, having its second hottest summer on record when looking at day time maximums. The day-time average for summer was 31.9 (this will change slightly), just short of the 32.2 record set in 1977/78. Milder temperatures through the first half of February were the only hindrance to the record being broken. The average maximum summer temperature in Perth is 30 degrees.
While all capital cities had a warmer than usual summer, large areas of inland Queensland had below average temperatures. This was due to periods of heavy rain and thick cloud cover associated with Tropical Cyclone Laurence in December and Olga in January.
Longreach had its coolest summer since 1975/76, based on the combined average of minimum and maximum temperatures. Day-time temperatures were around 3.6 degrees below the norm. Related rain events through inland NSW, northeastern SA and southern parts of the Northern Territory kept temperatures in these regions closer to average or just below.
Capital cities temperature summary:
Brisbane
Average min for summer 09/10: 21.9 Long term average: 20.8
Average max for summer 09/10: 30.5 Long term average 28.8
Sydney
Average min for summer 09/10: 20.4 Long term average: 18.3
Average max for summer 09/10: 26.9 Long term average 25.6
This average minimum for Sydney was the 2nd or 3rd warmest on record. The record was 20.7 in 1991 and in 20.2 in 1998. This will have to be finalised on Sunday.
Canberra
Average min for summer 09/10:14.8 Long term average: 12.6
Average max for summer 09/10:29.2 Long term average: 27.1
Melbourne
Average min for summer 09/10:16.3 Long term average: 13.9
Average max for summer 09/10: 27.3 Long term average: 25.3
Hobart
Average min for summer 09/10:12.7 Long term average: 11.6
Average max for summer 09/10:23.1 Long term average: 21.2
Adelaide: Average min for summer 09/10:17.7 Long term average: 16.5
Average max for summer 09/10: 30.5 Long term average: 28.5
Perth
Average min for summer 09/10: Long term average:
Average max for summer 09/10: Long term average:
This was the 2nd hottest summer on record for Perth based on daytime maximum temperatures (but not the 2nd hottest overall). Day time temperatures were more than 1.3 degrees above the long-term average, thanks largely to a very hot January and finish to February.
Darwin
Average min for summer 09/10:25.4 Long term average: 24.9
Average max for summer 09/10:32.5 Long term average: 31.9
These February minimum temperatures in Darwin were close to the warmest on record.
Major Weather Events for Summer 09/10
The tropical low intensified into tropical cyclone “Laurence” that was declared on the afternoon of Sunday 13th December. It was located to the northeast of the Kimberley area and continued on a WSW track, roughly parallel with the Kimberley coastline.
Tropical cyclone “Laurence” moved southwest roughly parallel to the Western Australian coastline on Monday and Tuesday 14th December, intensifying as it did so. By Wednesday 16th the cyclone had developed into a powerful category 5 system that later crossed the coast and weakened into a tropical low on Friday 18th.
After moving out to sea on Saturday 19th, tropical cyclone “Laurence” re intensified and moved back towards the coast, finally crossing near 80 Mile Beach as an intense category 5 system on the evening of Monday 21st. Widespread heavy rain and destructive winds battered the surrounding area.
Over the next seven days “Laurence” moved eastwards in an amazingly long journey, across parts of WA, SA, NSW and the Northern Territory, weakening into a rain depression but dumping heavy rain across all these areas. Flood warnings were later issued for the Castlereagh, Culgoa, Bokhara, Narran and Paroo Rivers.
The remnants of tropical cyclone “Laurence” moving slowly across northern NSW and southern Queensland during the week of 27th December to 2nd January produced widespread heavy rain across these areas. As the week progressed, more flood warnings were issued and flooding was eventually reported from 4 river systems in Queensland and 8 in NSW.
The Darling River produced significant flooding over northern inland NSW on Friday 1st January and this continued into the weekend of 2nd and 3rd January. Significant flooding was also reported from along the Castlereagh River with major floods developing around Coonamble.
Heavy rain across the Northern Territory occurred during Wednesday and Thursday 6th and 7th January producing 72 hour totals in excess of 100mm. The Todd River began to flow through the Alice Springs area.
Heatwave conditions built across south-eastern Australia from Thursday 7th onwards with Adelaide experiencing the highest capital city temperatures, exceeding 40C on three days in a row. An intense, rolling heat-wave affected South Australia, Victoria southern inland NSW and Tasmania from Sunday 10th January to Tuesday 12th January triggering the issue of catastrophic fire danger warnings in many areas.
Adelaide experienced 4 days in a row above 40C (from Friday 8th to Monday 11th January) and Melbourne’s temperature peaked at 43.6C on Monday 11th. Many rural parts of Victoria experienced their highest temperatures since Black Saturday 7th February 2009, and several of these were January records.
A strong cold front moving across south-eastern Australia produced light snowfalls across the NSW and Victorian ski-fields on the morning of Monday 18th January. This was in marked contrast to the burst of 40 plus temperatures that affected the same area the previous week.
Tropical cyclone “Olga” was declared on Friday 22nd January off the far north tropical coast of Queensland. It crossed the coastline near Cape Tribulation as a category 2 system on Sunday afternoon 24th January, and weakened into a rain depression, producing heavy falls across the adjacent areas.
“Olga” continued on an erratic path to the south of the Gulf of Carpentaria over the following 9 days, decaying and reforming on two occasions before striking southwards into central Queensland on Saturday 29th January.
Heavy falls resulted across large parts of Queensland on Monday 1st February producing some of the best rain in 30 years for the central west area. Strong onshore winds and king tides also produced dangerous surf conditions along parts of the Queensland coastline.
On Wednesday and Thursday, February 3rd and 4th, rain extended southwards into northern NSW and north-eastern parts of South Australia, producing heavy falls and local flooding. Roads were cut in parts of north-western NSW including areas around Tibooburra and Wanaaring.
Valuable rain fell across much of Victoria and southern NSW on Thursday and Friday, producing good falls in some of the drier parts of the mainland. Totals in excess of 50 mm were recorded across north-eastern Victoria and the Riverina area in NSW also received widespread falls in excess of 20 mm.
Severe thunderstorms swept across the Sydney metropolitan area and the NSW central coast on the afternoon of Friday 5th February, producing flash flooding and numerous lightning strikes. Sydney Airport was closed for half an hour at the height of the storm, and power cuts affected the Gosford-Narara area. Heavy rain also rolled across the Bega district of NSW producing 24-hour totals in excess of 100mm.
Heavy rain affected south-eastern Queensland, northeast NSW and the Sydney metropolitan area on Saturday night 6th February. Falls in excess of 100 mm in only 6 hours produced flash flooding in some of these areas.
Record rainfall drenched south-eastern Queensland on Saturday 6th and Sunday 7th February, with Canungra and Mount Tamborine receiving over 350 mm in the 24 hours ending at 9 am Sunday. These were the heaviest falls in over 90 years of records. Widespread flooding resulted across the local area.
Severe thunderstorms struck parts of Victoria, including the Melton and Bacchus Marsh areas, on the afternoon of Wednesday 10th February. Flash flooding was the main issue, as the storms were quite slow moving. Melbourne itself was hit, with 40 mm of rain falling in around an hour, producing flash flooding of city roads and power outages across the CBD and nearby suburbs.
Heavy rain struck Sydney on the night of Friday 12th, the result of widespread thunderstorm activity, producing 40 mm in just half an hour at Observatory Hill. This generated flash flooding in several localities, including the CBD and Northern Beaches areas.
Major flash flooding erupted across south-eastern Queensland, including Brisbane, on the afternoon of Tuesday, February 16, as severe thunderstorm activity ramped up across the area. Falls of 80 mm were recorded in just over an hour, producing widespread street flooding, power outages and transport dislocation.
Dick Whitaker
Senior Meteorologist
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