Monday, 2 September 2013 - Monthly Climate Summary for Western Australia - Product code IDCKGC21R0
Western Australia in August 2013: Second warmest August on record
- Rainfall: below average rainfall for WA, near average for southwest WA
- Maximum temperature: 2nd warmest for WA, 4th warmest for southwest WA
- Minimum temperature: above average for WA, 3rd warmest for southwest WA
Rainfall in August 2013 was below to very much below average over most of the Pilbara, Gascoyne, Goldfields, Northern and Southern Interior, and Eucla. Much of the Kimberley and Southwest Land Division (SWLD) reported near average August rainfall, although very light rainfall in the far north Kimberley in the middle of the month brought above average totals, given it rains rarely in the region in August. Small areas of the SWLD also recorded above to very much above average rainfall, particularly near the west and south coasts.
For WA as a whole, rainfall in August 2013 was below average, however averaged across the the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay), as well as for the wider SWLD region, rainfall during August 2013 was near average.
A weak cold front brushed through the southwest corner of WA on the first day of August, bringing generally light showers to parts of the SWLD, with some moderate falls in the Southwest, Lower West, and South Coastal districts. Northwesterly winds over the SWLD from the 4th to the 8th along with a slow moving cloudband and a cold front brought persistent showery conditions to much of the SWLD, with moderate to heavy falls reported in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) intially and extending through the SWLD on the 7th and 8th. Daily rainfall of 80.2 mm at Bickley (Perth hills) on the 8th was the highest daily rainfall of the month in WA, and it was the second wettest day in August at Bickley in 45 years of record, and the wettest day at the site for any month for over 12 years, since 137.0 mm was recorded on 30 July 2001. Gingin in the Lower West recorded a daily total of 52.8 mm, also on the 8th, which was the wettest day in August at the site in 107 years of record. The previous record at Gingin was 52.3 mm on 11 August 1944.
Light to moderate rainfall continued in the southwest of WA between the 9th and 14th under a persistent westerly airstream with embedded weak cold fronts. A strong cold front moved through southern WA on the 15th and 16th brining widespread rainfall to the SWLD and neighbouring parts of the Gascoyne, Goldfields, and Eucla. Esperance in the Southeast Coastal recorded a daily total of 47.2 mm on the 16th, the wettest August day in 45 years of recording at the site, exceeding the previous record of 40.2 mm on 27 August 2002, whilst Merivale Farm (Southeast Coastal) recorded a daily rainfall of 52.4 mm on the 16th, exceeding the previous highest August daily fall in its 31 years of record of 38.0 mm. A complex low pressure system and upper level trough moved through southern WA on the 25th and 26th bringing widespread rainfall to much of the SWLD, southern Gascoyne, and Goldfields, with moderate to heavy falls in the Central West, Lower West, and Southwest, followed by another low pressure system on the 27th and morning of the 28th, that brought further widespread rainfall to the SWLD and southern Gascoyne. A westerly stream prevailed over the SWLD from the 29th for the remainder of the month as weak cold fronts moved through the region bringing widespread rainfall with some moderate falls to western parts of the Division.
Very much above average mean maximum temperatures were observed across almost all of WA in August 2013, with areas over 4 °C warmer than normal in the southeast Northern Interior and the eastern coastal Eucla. Carnarvon Airport in the Gascoyne and a few sites in the Lower West observed their warmest or equal warmest August on record, including Perth Metro and Rottnest Island, with 116 and 115 years of record respectively. Only parts of the Pilbara coast recorded a near average August in terms of the mean maximum temperature.
Averaged across the state as a whole, the mean maximum temperature for WA in August 2013 was the second warmest from comparable records commencing in 1910. For the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) the mean maximum temperature was the fourth warmest on record.
A high moving over WA from the west in the early days of August 2013 produced a warming trend near the west coast, which resulted in unusually high temperatures in the west Gascoyne on the 3rd. Carnarvon Airport recorded its equal warmest day in August on record with a maximum of 31.6 °C, equal with the same maximum recorded on 11 August 1988. The unusually warm conditions extended through the southern half of WA on the 4th, and persisted until the 9th when the unusually high temperatures became confined to eastern central parts of the State where they continued until the 12th. Unusually hot days were reported in parts of the Kimberley and Northern Interior from the 12th to the 21st with daily maxima in the mid-to-high thirties at times. Warmun in the east Kimberley recorded a daily maximum of 39.5 °C on the 20th, which was the highest temperature in August 2013 in WA, and the highest August temperature at Warmun in 52 years of record, exceeding the previous record of 39.0 ºC on 31 August 2009. It was also the equal fourth highest temperature recorded in August in WA, only behind 40.0 ºC at Kalumburu Mission on 27 August 1970, 39.7 ºC at Wyndham Aerodrome on 31 August 2009, 39.6 ºC at Wyndham on 31 August 1985, and equal with 39.5 ºC at Derby Post Office on 24 August 1989.
Unusually warm days were evident in parts of the west Gascoyne and western SWLD from the 22nd to the 24th, whilst very warm days were reported in the Southern Interior and Eucla from the 25th to the end of the month.
Most of the southern half of WA, west Gascoyne, west Pilbara, and Northern Interior saw above to very much above average mean minimum temperatures in August 2013 with a number of sites in the SWLD recording their highest mean minimum on record . Mean minima up to 3 °C warmer than normal were recorded in the southern half of the SWLD and parts of the Northern Interior. Cape Leeuwin in the Southwest recorded a mean minimum of 13.5 °C, which was its highest August mean minimum in 116 years of record and 0.5 °C higher than the previous record in August 2006, as the result of warmer than normal sea surface temperatures near southwest WA. In contrast, below to very much below average mean minimum temperatures occurred in parts of the Kimberley, with means up to 3 °C cooler than normal reported.
Averaged across the state as a whole, the mean minimum temperature for WA in August 2013 was above average, whilst averaged across the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) the mean minimum temperature was the third warmest on record.
Cold nights were reported at various sites in the north and east Kimberley under clear skies and in very dry air between the 4th and 10th, with daily minima below 10.0 °C. Kununurra Aerodrome recorded a minimum of 7.0 °C on the 6th, overtaking its previous lowest temperature in August in 26 years of record of 7.3 °C registered on both 3 and 14 August 2012.
Mild nights were observed across large parts of the SWLD from the 5th to the 8th due to generally northwesterly winds and cloudy skies. Several sites in the Lower West and neighbouring Great Southern and Central Wheat Belt recorded their highest August minimum temperature on record on the 7th or 8th as a result. Perth Metro recorded a daily minimum 17.1 °C on the 7th, which was its warmest night in August since records commenced in 1897. The previous August record of 17.0 °C was observed exactly seven years previously on 7 August 2006.
Cold nights were experienced in parts of southern WA from the 11th to the 25th as a result of clear skies and light winds, with daily minima below 5.0 °C and a number of sites recording sub-zero temperatures. Eyre recorded the lowest temperature in the State on the 21st with a minimum of -1.8 ºC.
A suspected waterspout crossed the Perth metropolitan coast near North Coogee on the 6th, causing injury to 6 people (two serious) when scaffolding on a building site collapsed. Buildings were damaged and a heavy concrete building slab was lifted up.
|Extremes in August 2013|
|Hottest day||39.5 °C at Warmun on the 20th|
|Warmest days on average||35.5 °C at Wyndham Aero|
|Coolest days on average|| 16.1 °C at Manjimup
16.1 °C at Rocky Gully
|Coldest day||11.9 °C at Manjimup on the 15th|
|Coldest night||-1.8 °C at Eyre on the 21st|
|Coolest nights on average||4.7 °C at Yeelirrie|
|Warmest nights on average|| 25.3 °C at Browse
19.0 °C at Troscott
|Warmest night|| 26.6 °C at Browse
Island on the 22nd
24.4 °C at Wyndham Aero on the 23rd
|Wettest overall||325.0 mm at Mount William|
|Wettest day||80.2 mm at Bickley on the 8th|
|Highest wind gust||111 km/h at Cape Naturaliste on the 15th|
|Record highest August daily rainfall|
Highest daily rainfall
in August 2013 (mm)
|Gingin||52.8||on the 8th||52.3||on the 11th in 1944||107|
|Esperance||47.2||on the 16th||40.2||on the 27th in 2002||45|
|Merivale Farm||52.4||on the 16th||38.0||on the 11th in 1999||31|
|Record highest August temperature|
in August 2013 (°C)
|Carnarvon Airport||31.6||on the 3rd||= 31.6||on the 11th in 1988||67||23.0|
|Warmun||39.5||on the 20th||39.0||on the 31st in 2009||52||32.3|
|Record highest August mean daily maximum temperature|
| Mean daily maximum
for August 2013 (°C)
| Previous warmest
|Carnarvon Airport||25.4||= 25.4||in 1987||66||23.0|
|Perth Metro||20.4||20.3||in 1902||116||18.9|
|Pearce RAAF||20.2||= 20.2||in 2006||52||18.3|
|Rottnest Island||19.4||19.2||in 2006||115||17.8|
|Record highest August daily minimum temperature|
| Highest daily minimum
in August 2013 (°C)
| Previous warmest
|Perth Metro||17.1||on the 7th||17.0||on the 7th in 2006||116||8.0|
|Northam||14.7||on the 8th||14.5||on the 17th in 1999||104||5.6|
|Dwellingup||14.3||on the 8th||14.1||on the 3rd in 1983||54||5.4|
|Pearce RAAF||16.3||on the 7th||16.2||on the 23rd in 1966||54||8.1|
|Karnet||14.4||on the 8th||14.0||on the 26th in 1994||48||6.2|
|Brookton||13.8||on the 7th||13.4||on the 25th in 1970||46||4.6|
|Record highest August mean daily minimum temperature|
| Mean daily minimum
for August 2013 (°C)
| Previous warmest
|Cape Leeuwin||13.5||13.1||in 2006||116||11.2|
|Cape Naturaliste||12.1||12.0||in 2006||109||10.1|
|Bencubbin||8.2||= 8.2||in 2011||61||5.9|
|Summary statistics for August 2013|
|North Kimberley (district 01)|
|Wyndham Aero||35.5||+1.7||38.0||21st||16.6||+0.5||10.6||7th||0||0.1||v low||0%|
|East Kimberley (district 02)|
|Argyle Aerodrome||34.3||+2.3||39.2||20th||18.1||+0.8||12.5||6th||0||0.2||v low||0%|
|Halls Creek Airport||32.3||+2.3||36.6||20th||15.2||+0.4||7.8||6th||0||1.9||lowest||0%|
|West Kimberley (district 03)|
|Curtin Aero||34.5||+1.4||37.3||20th||15.0||-0.8||8.2||8th||0||1.7||v low||0%|
|Fitzroy Crossing Aero||35.2||+1.9||38.5||18th||13.3||-0.4||6.9||6th||0||1.2||v low||0%|
|De Grey (district 04)|
|Marble Bar||31.0||+0.8||33.4||15th||12.4||-0.7||7.9||5th||0||0.3||v low||0%|
|Port Hedland Airport||30.7||+1.5||33.7||20th||13.1||0.0||9.4||1st||0.2||4.8||low||4%|
|Fortescue (district 05)|
|Barrow Island Airport||25.6||+0.5||29.7||14th||17.7||-0.1||14.4||6th||0.8||2.9||low||28%|
|Fortescue Dave Forrest||28.4||30.6||15th||11.0||6.5||18th||0|
|West Gascoyne (district 06)|
|Emu Creek Station||29.3||+1.8||33.1||20th||12.4||+0.1||10.1||3rd||0||11.3||lowest||0%|
|Shark Bay Airport||25.5||+1.5||30.6||24th||11.5||+0.6||5.8||5th||5.8||19.1||v low||30%|
|East Gascoyne (district 07)|
|Murchison (district 07A)|
|Mount Magnet Aero||23.0||+1.9||28.7||7th||8.8||+1.1||5.7||17th||7.2||16.2||average||44%|
|North Coast (district 08)|
|Central Coast (district 09)|
|Badgingarra Research Stn||18.6||+0.4||25.2||24th||8.3||+1.3||4.6||16th||117.2||84.8||high||138%|
|Garden Island HSF||19.2||+1.2||21.9||23rd||13.1||+2.1||7.9||28th||125.2||91.3||high||137%|
|Gingin Aero||19.9||+1.0||26.7||24th||8.7||+2.4||2.8||24th||172.6||109.8||v high||157%|
|Jandakot Aero||19.8||+1.2||25.0||24th||9.9||+3.0||3.3||24th||194.6||126.4||v high||154%|
|Jurien Bay||21.2||+1.3||25.5||23rd||11.0||+1.7||6.0||22nd||132.6||81.5||v high||163%|
|Medina Research Centre||10.7||+2.7||5.1||20th|
|South Coast (district 09A)|
|Cape Naturaliste||18.0||+1.6||20.9||24th||12.1||+2.0||6.8||16th||168.4||112.4||v high||150%|
|Rocky Gully||16.1||+0.8||21.8||24th||8.3||+1.6||3.4||16th||2.8||85.7||v low||3%|
|North Central (district 10)|
|South Central (district 10A)|
|Newdegate Research Station||17.4||+1.2||23.0||24th||6.7||+2.6||-0.6||14th||42.8||43.4||average||99%|
|Eucla (district 11)|
|Red Rocks Point||21.8||29.7||8th||8.6||4.7||20th||10.8||40.6||v low||27%|
|South East (district 12)|
|Laverton Aero||23.2||+2.6||28.6||8th||8.0||+0.9||2.8||17th||0||8.7||v low||0%|
|Leinster Aero||23.2||+1.7||28.6||8th||8.5||+1.0||4.6||17th||0||8.9||v low||0%|
|Salmon Gums Res.Stn.||19.5||+2.1||25.7||24th||6.6||+2.0||-0.7||20th||25.6||32.9||average||78%|
|Southern Cross Airfield||19.9||+1.4||26.3||7th||6.3||+2.9||1.6||22nd||36.4||28.7||high||127%|
|North East (district 13)|
|Giles Meteorological Office||26.0||+3.4||31.6||28th||9.8||+1.1||3.9||17th||0||10.0||lowest||0%|
|Offshore Islands (district 200)|
|Christmas Island Aero||26.3||+0.3||27.0||10th||22.8||+0.6||21.2||1st||34.6||41.9||average||83%|
|Cocos Island Airport||28.1||0.0||29.0||14th||24.7||+0.8||22.2||21st||69.6||120.9||average||58%|
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 11 am on Monday 2 September 2013. 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, as they cannot then be calculated reliably.
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.
The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.