Tuesday, 3 January 2012 - Monthly Climate Summary for Western Australia - Product code IDCKGC31R0
Western Australia in December 2011: Third wettest December for southwest WA
- Rainfall: Near average for WA; 3rd wettest December for southwest WA.
- Maximum temperature: Near average.
- Minimum temperature: Near average for WA; 4th warmest for southwest WA.
Rainfall in WA during December 2011 was above to very much above average for most of the Southwest Land Division (SWLD), adjacent parts of the Goldfields, and the southeast Gascoyne, with numerous sites in the SWLD (many with over 100 years of record) registering their wettest December on record, mainly due to extremely heavy rainfall events on the 6th and 12th. Above to very much above average rainfall was also observed in the Interior and inland Kimberley, where the highest rainfall totals for December in WA were recorded, and the coastal Eucla, while below to very much below average rainfall was evident through much of the Pilbara and northwest Gascoyne, the coastal Kimberley, and inland Eucla (see the December 2011 rainfall totals & deciles maps).
When averaged across the state, December 2011 rainfall was near average, however for both the SWLD and the Lower Southwest (southwest a line from Jurien Bay to Bremer Bay), December 2011 ranked as 3rd wettest on record. Comparative rainfall records commenced in 1900.
A deep middle level trough off the west coast produced the first significant summer rainfall in the SWLD and the adjacent Goldfields and Gascoyne on the 6th. Numerous sites in the Lower West, Central Wheat Belt, and Great Southern observed over 50 mm during the event, though the heaviest downpours occurred in the eastern Central Wheatbelt and northeast Great Southern. Daily rainfall totals of 109.0 mm at Amrista Park and 105.0 mm at Hyden, both in the northeast Great Southern, in the 24 hours to 9am on the 7th were not only their wettest December days on record, but also their highest daily rainfall total for any month, and in the top ten highest December daily falls on record in the SWLD. Many other sites in the SWLD also broke their previous wettest December day on record on the 7th.
Another deep mid-level trough off the west coast brought further widespread moderate to heavy rainfall across the SWLD and the adjacent Goldfields and Gascoyne on the evening on the 12th and into the morning of the 13th, with numerous sites in the SWLD and Gascoyne observing their highest December daily rainfall on record. Areas in the Great Southern were hit hardest by the downpour, and the daily total of 125.6 mm at Williams in the Great Southern in the 24 hours to 9am on the 13th was not only their wettest December day in 115 years of record, but also the highest daily rainfall recorded in December in the SWLD. For more details of these two extreme heavy rainfall events, please see Special Climate Statement 35.
Mean daily maximum temperatures in WA during December 2011 were below to very much below average over eastern parts of the SWLD, the Goldfields, western Eucla, and southern Interior, with areas up to 3 °C cooler than normal in the southern Interior, eastern Goldfields, and far western Eucla. Below average daytime temperatures were also observed in coastal parts of the Pilbara, despite extremely hot days in the week prior to Christmas with temperatures in the high 40s. Above to very much above average maxima were observed along the west coast of WA, extending into the northern Gascoyne and inland Pilbara. Western and northern parts of the Kimberley also saw above average mean maxima, with temperatures up to 3 °C above normal (see the December 2011 mean maximum temperature deciles & anomaly maps) recorded around King Sound in the Kimberley, and Shark Bay in the Gascoyne.
When averaged across WA as a whole, daytime temperatures were near average for December 2011.
Extremely hot weather was observed in the Pilbara from the 20th through to the 25th, with numerous sites observing daily maxima over 47 °C, and several sites registering record high December temperatures. The December maximum temperature record for WA was also broken on three consecutive days, with Roebourne (49.4 °C on the 21st), Roebourne Airport (49.0 °C on the 21st), Onslow (49.2 °C on the 22nd), and Learmonth Airport (48.9 °C on the 23rd), all surpassing the previous December record of 48.8 °C set at Mardie on 26 December 1986. To further illustrate the significance of the event, Roebourne's 49.4 °C was the 2nd hottest December day on record in Australia, just 0.1 °C below the 49.5 °C recorded at Birdsville in Queensland on 24 December 1972, and the 5th hottest day on record in WA. Sites in WA have recorded temperatures of over 48 °C during December on 18 occasions, and 10 of those occurred during this event.
Mean daily minimum temperatures in WA in December 2011 were above to very much above average over large parts of western and southern WA, as well as in the west Kimberley, with up to 3 °C warmer than normal mean minima in the southwest Gascoyne, Central West, and Lower West. Several sites in western parts of the SWLD registered record high December mean minima, including Donnybrook in the Southwest, which has 105 years of record. Broome Airport also recorded its warmest December nights in 72 years of record. Below to very much below average overnight temperatures were reported in the central and southeast Kimberley, and northern and central Interior, with a small patch of up to 3 °C cooler than normal minima in the central Interior (see the December 2011 minimum temperature deciles & anomaly maps).
When averaged across the state, overnight temperatures in WA in December 2011 were below average, however, the Lower Southwest observed its 4th warmest December on record. Comparable temperature records commenced in 1950.
Hot nights were observed in the inland Pilbara from the 20th through to the 26th, with several sites observing minimum temperatures over 30 °C after extremely hot days. Wittenoom observed the hottest night for December 2011 with 33.2 °C on the 22nd, closely followed by Paraburdoo with 33.0 °C on the 26th.
Heavy rainfall and thunderstorms on the 6th caused flash flooding, flooded roads, fallen trees and minor damage to homes in Perth and Northam.
Thunderstorms and flash flooding occurred across parts of the SWLD, including the Perth Metropolitan area on the 12th. In the Great Southern region, there was significant flooding in Williams and Narrogin with homes and roads flooded. There were also reports of minor damage to roofs, fallen trees on homes, cars and fences.
|Extremes in December 2011|
|Hottest day|| 49.4 °C at Roebourne
on the 21st
49.2 °C at Onslow Airport on the 22nd
49.0 °C at Roebourne Aero on the 21st
48.9 °C at Learmonth Airport the 23rd
|Warmest days on average||42.5 °C at Marble Bar|
|Coolest days on average||22.2 °C at Albany|
|Coldest day||16.5 °C at Mount Barker on the 13th|
|Coldest night||4.1 °C at Salmon Gums Res.Stn. on the 26th|
|Coolest nights on average||12.5 °C at Jacup|
|Warmest nights on average|| 27.9 °C at Troughton
27.7 °C at Broome Airport
|Warmest night||33.2 °C at Wittenoom on the 22nd|
|Wettest overall||289.8 mm at Doongan|
|Wettest day||138.8 mm at Mount Krauss on the 29th|
|Highest wind gust||100 km/h at Halls Creek Airport on the 21st|
|Record highest December daily rainfall|
Highest daily rainfall
in December 2011 (mm)
|Pingelly||72.2||on the 7th||61.0||on the 30th in 1999||111|
|Gingin||76.0||on the 7th||66.0||on the 16th in 1923||107|
|Katanning Comparison||63.0||on the 13th||54.9||on the 3rd in 1940||106|
|Codg Codgen||76.6||on the 7th||53.0||on the 25th in 1991||105|
|Wagin||87.0||on the 13th||66.0||on the 24th in 1987||105|
|Williams||125.6||on the 13th||74.2||on the 22nd in 1958||105|
|Narrogin||84.4||on the 13th||57.8||on the 31st in 1980||104|
|Darkan||64.8||on the 13th||53.3||on the 29th in 1912||102|
|Bannister||105.4||on the 13th||57.6||on the 31st in 1980||101|
|Dumbleyung||71.0||on the 13th||51.0||on the 31st in 1983||101|
|Trayning||70.4||on the 7th||35.8||on the 3rd in 1940||101|
|Belka||72.0||on the 7th||51.1||on the 20th in 1913||100|
|Rushy Pool||70.0||on the 13th||61.5||on the 1st in 1951||100|
|Arthur River||71.0||on the 13th||53.4||on the 23rd in 1987||99|
|Kukerin||61.0||on the 13th||50.2||on the 31st in 1980||98|
|Bruce Rock||62.0||on the 7th||44.5||on the 18th in 1952||95|
|Dellyanine||70.0||on the 13th||64.0||on the 24th in 1987||92|
|Koorda||40.0||on the 7th||36.8||on the 19th in 1978||90|
|Nairibin||67.0||on the 13th||49.0||on the 31st in 1980||89|
|Narembeen||87.4||on the 7th||39.6||on the 24th in 1987||85|
|Hyden||105.0||on the 7th||47.2||on the 3rd in 1940||83|
|Hines Hill||65.6||on the 7th||63.2||on the 24th in 1995||81|
|Holt Rock||42.4||on the 7th||28.2||on the 17th in 1960||80|
|Woodanilling||58.6||on the 13th||51.8||on the 3rd in 1940||76|
|Karlgarin||94.0||on the 7th||48.0||on the 24th in 1987||75|
|Beacon||41.0||on the 7th||29.2||on the 12th in 1930||73|
|Lake King||44.0||on the 7th||43.2||on the 3rd in 1940||73|
|Seven Oaks||50.0||on the 7th||38.4||on the 19th in 1978||73|
|Perth Airport||35.2||on the 13th||27.2||on the 3rd in 1951||68|
|Pearce RAAF||48.8||on the 7th||34.5||on the 18th in 1952||57|
|Amrista Park||109.0||on the 7th||58.0||on the 25th in 1987||56|
|Mount Walker||59.0||on the 7th||32.8||on the 17th in 1960||54|
|Swanara||90.0||on the 7th||43.4||on the 24th in 1987||51|
|Kojonolokan Hills||60.0||on the 13th||35.0||on the 1st in 2001||49|
|Spring Valley||70.0||on the 7th||64.4||on the 24th in 1995||49|
|Allan Rocks||65.6||on the 7th||34.8||on the 7th in 1987||44|
|Roleystone||40.0||on the 7th||28.4||on the 27th in 1966||44|
|Mordetta||74.0||on the 7th||42.0||on the 25th in 1987||37|
|Gibb Rock||49.0||on the 7th||28.4||on the 23rd in 1987||31|
|Record highest total December rainfall|
for December 2011 (mm)
|Katanning Comparison||85.4||74.4||in 1951||119||16.6|
|Codg Codgen||95.2||75.6||in 1991||110||11.8|
|Lake Grace Comparison||93.4||70.2||in 1913||100||15.0|
|Bruce Rock||124.0||60.7||in 1923||95||13.1|
|Hines Hill||98.4||86.4||in 1995||80||9.2|
|Mount Madden||97.0||91.7||in 1987||80||16.6|
|Lake King||120.4||67.3||in 1940||73||15.5|
|Perth Airport||65.8||65.5||in 1951||68||11.2|
|Newdegate Research Station||136.0||66.9||in 1980||58||15.3|
|Amrista Park||135.8||132.6||in 1987||56||16.0|
|Mount Walker||87.4||72.0||in 1987||55||13.7|
|Dandaragan West||64.2||50.4||in 2007||54||9.7|
|Kojonolokan Hills||78.6||57.7||in 1983||49||14.9|
|Pearce RAAF||65.0||53.6||in 1952||49||10.2|
|Esperance Aero||66.0||59.0||in 1983||41||20.4|
|Pickering Brook||55.1||34.9||in 1984||34||14.4|
|Desert Fringe||87.0||70.0||in 2008||31||17.7|
|Record highest December temperature|
| Highest temperature
in December 2011 (°C)
| Previous warmest
|Roebourne||49.4||on the 21st||47.6||on the 31st in 1969||55||39.0|
|Onslow||48.7||on the 22nd||47.3||on the 23rd in 1980||51||35.2|
|Onslow Airport||49.2||on the 22nd||47.3||on the 12th in 1950||46||35.9|
|Learmonth Airport||48.9||on the 23rd||46.8||on the 21st in 2004||37||36.8|
|Marble Bar||48.4||on the 21st||48.3||on the 29th in 1956||117||41.6|
|Record highest December mean daily minimum temperature|
Mean daily minimum
for December 2011 (°C)
|Broome Airport||27.7||27.5||in 2002||72||26.5|
|Pearce RAAF||17.3||17.1||in 2002||52||14.4|
|Summary statistics for December 2011|
|North Kimberley (district 01)|
|East Kimberley (district 02)|
|Halls Creek Airport||37.1||-0.7||40.9||26th||24.2||-0.5||20.3||4th||150.4||82.1||v high||183%|
|West Kimberley (district 03)|
|Broome Airport||34.5||+0.7||40.5||2nd||27.7||+1.2||23.9||29th||0.2||56.0||v low||0%|
|Fitzroy Crossing Aero||39.6||+0.5||44.2||1st||24.8||-0.9||21.8||3rd||85.4||121.1||low||71%|
|West Roebuck||36.6||+0.8||41.6||22nd||25.6||+0.4||23.0||22nd||8.2||103.7||v low||8%|
|De Grey (district 04)|
|Port Hedland Airport||35.6||-1.0||43.0||20th||24.7||+0.7||21.6||5th||0||18.1||lowest||0%|
|Roebourne Aero||38.9||-0.3||49.0||21st||24.5||-0.1||21.1||2nd||0||5.6||v low||0%|
|Fortescue (district 05)|
|Barrow Island Airport||31.8||-0.2||39.2||24th||24.6||+0.3||22.6||1st||0||3.0||v low||0%|
|West Gascoyne (district 06)|
|Emu Creek Station||40.1||+0.3||48.2||24th||22.8||+0.5||17.6||7th||0||13.2||lowest||0%|
|Shark Bay Airport||33.0||+0.9||42.9||27th||20.7||+1.3||17.6||2nd||0.6||12.8||average||5%|
|East Gascoyne (district 07)|
|Murchison (district 07A)|
|Mount Magnet Aero||34.0||-1.5||41.4||22nd||20.9||-0.1||17.3||8th||67.0||24.3||high||276%|
|North Coast (district 08)|
|Geraldton Airport Comparison||31.4||+1.9||40.2||28th||18.4||+2.1||14.6||17th||1.0||5.4||average||19%|
|Central Coast (district 09)|
|Badgingarra Research Stn||31.9||-0.1||40.1||28th||17.0||+2.1||10.7||19th||43.4||9.7||v high||447%|
|Garden Island HSF||27.6||+2.4||37.9||28th||18.8||+1.9||15.9||1st||38.8||9.7||v high||400%|
|Gosnells City||30.9||+0.7||39.6||28th||18.4||+2.4||13.9||19th||55.4||11.5||v high||482%|
|Jandakot Aero||30.1||+1.2||39.1||28th||16.7||+2.2||10.0||19th||39.0||10.5||v high||371%|
|Medina Research Centre||30.1||+2.2||39.6||28th||17.7||+2.8||12.9||19th||51.8||10.6||v high||489%|
|Perth Metro||30.5||+1.7||39.9||28th||18.2||+2.0||13.3||19th||75.8||12.8||3rd highest||592%|
|South Coast (district 09A)|
|Busselton Aero||29.3||+1.5||37.7||29th||14.4||+2.1||8.4||20th||14.8||8.7||v high||170%|
|Cape Naturaliste||27.1||+3.6||34.2||28th||15.7||+1.8||12.1||20th||39.0||13.5||v high||289%|
|Collie East||28.2||37.5||29th||13.6||9.3||1st||44.2||14.1||v high||313%|
|Hopetoun North||24.1||-0.1||36.1||30th||14.8||+0.8||9.5||1st||84.4||26.2||v high||322%|
|North Central (district 10)|
|South Central (district 10A)|
|Lake Grace||28.0||-1.3||37.4||29th||15.0||+1.7||10.6||1st||91.2||19.8||v high||461%|
|Lake Grace Comparison||28.0||-1.6||37.6||29th||14.9||+1.5||10.5||1st||93.4||15.0||highest||623%|
|Newdegate Research Station||28.2||-0.9||37.5||30th||13.6||+2.0||9.1||26th||136.0||15.3||highest||889%|
|Eucla (district 11)|
|Red Rocks Point||23.0||35.6||31st||17.4||12.3||12th||62.8||18.3||v high||343%|
|South East (district 12)|
|Bulga Downs||34.0||41.7||23rd||18.9||13.8||2nd||57.6||13.4||v high||430%|
|Salmon Gums Res.Stn.||28.8||-0.1||41.0||22nd||13.6||+1.4||4.1||26th||34.2||20.2||high||169%|
|Southern Cross Airfield||30.8||-1.9||38.3||30th||16.7||+1.6||12.6||17th||91.4||17.4||v high||525%|
|North East (district 13)|
|Giles Meteorological Office||34.7||-1.0||40.9||25th||20.5||-1.4||13.3||4th|
|Offshore Islands (district 200)|
|Christmas Island Aero||28.1||+0.4||29.9||27th||23.1||+0.6||21.6||3rd||358.0||214.6||high||167%|
|Cocos Island Airport||29.7||+0.3||30.9||8th||25.2||+0.7||23.1||7th||162.4||115.6||high||140%|
|Varanus Island||31.4||+0.3||37.0||21st||24.7||0.0||23.1||7th||0||2.1||v low||0%|
A Monthly Climate Summary is prepared to list the main features of the weather in Western Australia using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.
This statement has been prepared based on information available at 10 am on Tuesday 3 January 2012. Some checks have been made on the data, but it is possible that results will change as new information becomes available.
Averages are long-term means based on observations from all available
years of record, which vary widely from site to site. They are not shown for
sites with less than 10 years of record.
The median is sometimes more representative than the mean of long-term average rain.
The Rank indicates how rainfall this time compares with the climate record for the site,
based on the
(very low rainfall is in decile 1, low in decile 2 or 3,
average in decile 4 to 7, high in decile 8 or 9
and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.
Records in this summary are based on sites with at least 30 years of data.