Western Australia in September 2012: A very warm month

  • Rainfall: near average for WA
  • Maximum temperature: 4th highest for WA; above average for southwest WA
  • Minimum temperature: above average for WA; near average for southwest WA

Rainfall

Rainfall in western parts of the Southwest Land Division (SWLD) was near average to above average during September 2012, with some small areas of very much above average rainfall. In contrast, below to very much below average rainfall was observed in much of southeastern and central WA (see the maps below). For the remainder of the state, rainfall was a mixture of above and below average, although rainfall totals are typically low in northern WA during September.

Averaged across WA, September rainfall was near average. After the 6th driest winter on record in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay), rainfall during September was near normal when averaged across the region. Parts of the region reported above average September rainfall, and Wokalup in the Southwest and Walpole in the South Coastal observed their wettest September on record, whilst sites in western parts of the Great Southern registered their wettest September for over 30 years.

A strong cold front moved through western parts of WA on the 3rd and into central parts of the state during the morning of the 4th, with widespread moderate rainfall observed through the western SWLD, and lighter falls extending into eastern parts of the SWLD, Gascoyne, west Pilbara, and Goldfields. Heavy rainfall in the 40 to 70 mm range was observed at a number of locations in the Southwest and Lower West districts in the 24 hours to 9am on the 4th. Bickley recorded the highest daily total with 67.2 mm, which is the 4th highest September daily total for the site in 44 years of record, and the highest daily total in WA for September 2012. Strong winds were observed in parts of the SWLD with the passage of the front during the afternoon and evening of the 3rd, particularly along the Lower West coast where gusts of over 90 km/h were recorded. Strong winds continued in the wake of the front around the Southwest Capes on the 4th, with Cape Naturaliste and Cape Leeuwin observing wind gusts of 117 km/h and 115 km/h respectively and moderate rainfall totals were observed in western and southern parts of the SWLD after very heavy rainfall the previous day. Reports of snow on Bluff Knoll in the Stirling Ranges were also received on the 4th. A strong cold front on the 21st brought moderate to heavy rainfall to the Lower West, Southwest, and South Coastal districts and strong gusts to the Southwest Capes, with Cape Leeuwin observing winds to 115 km/h. An unstable westerly flow lay over southwestern WA on the 26th and a cold front crossing the area during the afternoon and overnight resulted in moderate to heavy falls in the 24 hours to 9am on the 27th in the Southwest, Lower West, and South Coastal districts. Showers and thunderstorms on the last day of September 2012 brought moderate to heavy rainfall to the northern Interior, inland Kimberley and inland east Pilbara.

Despite the near average September, the Lower Southwest has recorded its 8th driest January to September period on record, largely as a result of registering its 8th driest autumn, and 6th driest winter, which included the driest July on record since comparable records commenced in 1900.

Maximum temperature

Maximum temperatures during September were above to very much above average throughout almost all of WA with areas of highest on record in eastern and northern parts of the state. Eastern parts of the Eucla, parts of the Interior, and western parts of the Kimberley saw mean maximum temperatures up to 4 °C warmer than normal, and Eucla and Eyre, both in the Eucla district, observed their equal warmest and warmest September on record respectively. Esperance, in the neighbouring South Coastal, and Warburton, in the Interior, observed their 3rd warmest Septembers in 43 and 38 years of record respectively.

When averaged across the state as a whole, the mean maximum temperature during September 2012 ranked as 4th highest on record for WA, continuing a run since April of six consecutive above average months. Mean maximum temperatures were also above average in the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) and September 2012 continued the very warm year to date in the region. Almost all months so far in 2012, apart from February, have seen above average mean maxima in the Lower Southwest, with the mean maximum for January to September 2012 being 0.9 °C above normal and ranking equal 3rd highest since comparable temperature records commenced in 1950. The very much above average year so far is largely due to an above average January, a very much above average autumn (5th warmest), and an above average July to September. The run of "warm" temperatures has persisted for three years as the Lower Southwest has only recorded two months below the average, in terms of mean maximum temperature, since October 2009.

A very hot day was observed over the SWLD on the 9th as a high over southeast Australia and a trough off the west coast directed northerly winds over the area. Temperatures were in the low twenties in southwestern parts of the division, grading to the high twenties in central and eastern parts, and into the low thirties in the Central West. The hot conditions moved over central and southern parts of the state on the 10th in northerly winds ahead of a cold front, with particularly hot temperatures for September observed in the Southeast Coastal, southern Goldfields, and western Eucla, where temperatures were in the high twenties to low thirties. Temperatures reached the low forties in the Kimberley on the 13th and 14th, then again from the 23rd through to the 28th. Kununurra Aerodrome in the Kimberley registered its hottest September day in 27 years of record with 41.1 °C on the 24th breaking the previous record of 41.0 °C set on 25 September 1989, while Argyle Aerodrome in the Kimberley observed its hottest September temperature in 19 years of record twice, with 40.7 °C on the 27th followed by 40.8 °C on the 28th, both breaking the previous record of 40.5 °C set on 30 September 1998.

A cool, cloudy, and showery day across western and central parts of WA on the 4th saw unusually low maximum temperatures recorded. Brookton in the Great Southern recorded a maximum temperature of 10.6 °C, its equal coolest September day in 45 years of record, equal with a maximum of 10.6 °C recorded on 22 September 1968, while Mount Barker in the South Coastal observed the coldest day in WA during September 2012 with a maximum of just 9.8 °C. Another very cold day was observed in the southwest of the state in the wake of a cold front on the 27th, with Karnet in the Lower West recording a maximum of 9.9 °C and most other sites in the area only reaching the low teens.

Minimum temperature

Below to very much below average minimum temperatures were observed in the northern Kimberley during September 2012, contrasting with above to very much above average overnight temperatures for much of the remainder of the state. Minimum temperatures were particularly high in the far eastern Pilbara and northern Interior where mean minima were over 3 °C above normal. When averaged across WA as a whole, mean minimum temperatures were above average in September 2012, whilst for the Lower Southwest, mean minimum temperatures were near average.

A cold front moving through the southern half of WA on the 27th was followed by a strong southerly stream which brought cold air to southwest WA. Minimum temperatures on the 28th were unusually low as a result and a number of sites recorded sub-zero minima. Karnet in the Lower West recorded a minimum of -0.6 °C, its lowest September temperature in 46 years of recording.

Consistently below average overnight minima for WA from January to August 2012 resulted in the state recording its third coolest January to August period on record; however, the above average September has seen WA's mean minimum for the year to date rise to 8th coolest on record. In contrast, the Lower Southwest has recorded an above average January to September period in terms of mean minimum temperature, with only two months in 2012 (May and July) recording below average mean minima, the only two months to do so since November 2010.

Further information

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Extremes in September 2012
Hottest day 41.9 °C at Curtin Aero on the 23rd
Warmest days on average 38.5 °C at Curtin Aero
Coolest days on average 17.6 °C at Rocky Gully
Coldest day 9.8 °C at Mount Barker on the 4th
Coldest night -2.5 °C at Eyre on the 30th
Coolest nights on average 3.6 °C at York
Warmest nights on average 21.1 °C at Argyle Aerodrome
Warmest night 27.1 °C at Argyle Aerodrome on the 28th
Wettest overall 240.7 mm at Walpole
Wettest day 67.2 mm at Bickley on the 4th
Highest wind gust 117 km/h at Cape Naturaliste on the 4th

Maps
ObservedAnomalyDecile rank
Total
rainfall
Map of Rainfall totals Map of Percentage of normal rainfall Map of Rainfall deciles
Mean
daily
maximum
temperatures
Map of Mean maximum temperature Map of Anomaly in mean maximum temperature Map of Decile rank of mean maximum temperature
Mean
daily
minimum
temperatures
Map of Mean minimum temperature Map of Anomaly in mean minimum temperature Map of Decile rank of mean minimum temperature

Record highest total September rainfall
Total rainfall
for September 2012 (mm)
Previous wettest
for September
Years of
record
Average for
September
Walpole 240.7 239.6 in 2003 61 137.8
Wokalup 214.2 184.0 in 1996 60 96.1

Highest total September rainfall for at least 30 years
Total rainfall
for September 2012 (mm)
Most recent September
at least this wet
Years since
wetter
Average for
September
Narrogin 79.4 88.6 in 1973 39 46.4
Williams 82.2 83.2 in 1973 39 50.9
Karnet 219.4 280.7 in 1973* 37 131.7

* note: there are gaps in the historical record at this site, so it is possible a higher value has gone unreported.




Record lowest September daily maximum temperature
Lowest daily maximum
temperature
in September 2012 (°C)
Previous coolest
for September
Years of
record
Average for
September
Brookton 10.6 on the 4th = 10.6 on the 22nd in 1968 45 19.1



Record highest September mean daily maximum temperature
Mean daily maximum
temperature
for September 2012 (°C)
Previous warmest
for September
Years of
record
Average for
September
Eucla 24.0 = 24.0 in 1981 75 21.3
Eyre 24.1 23.7 in 2008 52 21.1



Record lowest September temperature
Lowest temperature
in September 2012 (°C)
Previous coolest
for September
Years of
record
Average for
September
Karnet -0.6 on the 28th 0.0 on the 22nd in 2008 46 7.2



Summary statistics for September 2012
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2012
Diff
from
average
Highest for
September
2012
Mean for
September
2012
Diff
from
average
Lowest for
September
2012
Total for
September
2012
Average
for
September
Rank of
September
2012
Fraction of
September
average
North Kimberley (district 01)
Doongan 35.7 +0.4 38.2 25th 15.3 -2.4 9.7 3rd 0 5.4 v low 0%
Kalumburu 35.9 +0.3 39.2 13th                
Mount Elizabeth 35.1 +1.0 38.2 23rd 13.8 -1.2 7.4 11th 0 8.6 lowest 0%
Truscott 33.5   36.2 11th          
Wyndham 37.3 +0.6 40.1 24th 20.7 -2.1 17.1 17th 0 4.0 lowest 0%
Wyndham Aero 38.2 +0.6 40.8 24th 19.6 -2.3 15.5 16th 0 4.1 v low 0%
East Kimberley (district 02)
Argyle Aerodrome 37.3 +0.9 40.8 28th 21.1 -1.2 16.8 9th 0 2.6 v low 0%
Halls Creek Airport 35.5 +1.5 39.7 23rd 19.7 +0.7 15.2 10th 0 4.6 lowest 0%
Kununurra Aero 37.9 +1.4 41.1 24th 16.6 -3.7 12.5 11th 0 3.1 lowest 0%
Warmun 37.1 +1.0 41.0 28th         0 4.6 lowest 0%
West Kimberley (district 03)
Bidyadanga 34.4 +1.6 40.2 23rd         0.6 1.3 high 46%
Broome Airport 33.1 +1.3 38.8 13th 17.9 -0.6 13.8 13th 1.2 1.4 average 86%
Curtin Aero 38.5 +2.1 41.9 23rd 17.0 -1.5 11.9 1st 0 0.2 v low 0%
Cygnet Bay 33.1 +0.6 35.3 27th 16.8 -1.1 12.7 12th 0 1.4 lowest 0%
Derby Aero 36.7 +1.5 40.7 23rd 17.9 -1.7 12.8 11th 0 1.1 lowest 0%
Fitzroy Crossing Aero 38.5 +1.3 41.9 25th 18.0 -0.7 12.5 11th 0 0.4 v low 0%
West Roebuck 36.0 +1.7 41.0 23rd 16.8 -0.7 12.8 1st 0.6 0.6 average 100%
De Grey (district 04)
Karratha Aero 31.6 +1.0 36.1 16th 16.8 -0.1 12.2 6th 0 1.4 lowest 0%
Mandora 35.5 +1.9 39.1 14th 15.6 -0.1 10.9 3rd 1.4 1.0 v high 140%
Marble Bar 36.2 +1.8 39.4 26th 18.0 +1.4 10.5 6th 0 5.6 v low 0%
Pardoo Station 34.6 +1.8 38.5 26th         0 2.8 lowest 0%
Port Hedland Airport 34.3 +2.0 38.2 15th 15.9 +0.5 11.9 6th 0.6 1.3 average 46%
Roebourne 34.9 +2.3 39.0 15th 17.2 +0.4 11.8 6th 0 1.4 lowest 0%
Roebourne Aero 34.7 +1.9 38.6 24th 15.7 +0.2 10.6 6th 0.2 3.1 average 6%
Fortescue (district 05)
Barrow Island Airport 27.0 +0.3 31.7 30th 19.9 +0.6 16.9 6th 0.4 0.8 average 50%
Learmonth Airport 30.0 +0.7 35.4 13th 14.3 +0.5 10.0 5th 0 2.0 lowest 0%
Mardie 32.1 -0.1 36.3 16th 15.0 +0.7 11.2 6th 0 1.4 lowest 0%
Onslow Airport 30.6 +0.6 36.5 13th 17.0 +1.7 12.9 6th 0.2 1.5 average 13%
Wittenoom 33.3 +2.2 37.3 16th 17.4 +0.6 10.0 6th 0 3.2 lowest 0%
West Gascoyne (district 06)
Carnarvon Airport 25.9 +1.5 33.6 8th 14.8 +1.0 8.2 5th 4.0 5.6 average 71%
Denham 24.9 +1.2 32.7 8th         8.0 7.8 average 103%
Emu Creek Station 31.5 +0.9 36.7 30th 14.7 +0.7 11.1 5th 0 2.0 lowest 0%
Murchison 27.7 +1.7 34.0 30th 9.8 +0.6 3.5 29th 7.6 7.7 average 99%
Shark Bay Airport 26.5 +0.8 32.7 30th 13.6 +1.1 8.8 29th 18.2 8.1 v high 225%
East Gascoyne (district 07)
Newman Aero 31.7 +1.5 36.6 17th 13.8 +2.0 6.2 6th 0.8 4.4 average 18%
Paraburdoo Aero 32.6 +1.5 36.9 15th 14.5 +1.1 8.9 6th 0.4 3.5 average 11%
Murchison (district 07A)
Meekatharra Airport 27.1 +1.5 34.0 16th 12.1 +0.6 4.7 5th 1.8 4.8 average 38%
Mount Magnet Aero 26.1 +1.8 33.9 16th 11.3 +1.2 4.8 28th 6.2 9.1 average 68%
Paynes Find                 3.8 14.2 low 27%
North Coast (district 08)
Carnamah 22.9 +0.9 31.5 16th 9.3 +1.2 4.0 28th 28.5 28.1 average 101%
Dalwallinu 21.6 +0.8 30.2 16th 7.5 +0.9 2.6 28th 27.2 26.3 average 103%
Eneabba                 53.9 45.1 average 120%
Geraldton Airport 23.8   31.9 30th 10.0   3.5 30th 25.4
Geraldton Airport Comparison 23.7 +1.7 32.0 16th 10.1 +0.9 3.8 29th 20.6 31.8 average 65%
Kalbarri 25.7 +1.8 32.5 8th 12.2 +1.5 7.9 2nd 23.0 23.5 average 98%
Morawa Airport 23.8 +1.0 32.8 16th 8.8 +1.5 2.0 28th 16.4 24.5 low 67%
Mullewa 25.0 +1.6 33.8 16th 10.6 +2.1 5.4 5th 21.6 21.7 average 100%
North Island 23.1 +1.2 27.5 8th 16.2 +0.4 11.5 4th 19.0 22.2 average 86%
Wongan Hills 21.4 +0.8 29.5 30th 8.1 +0.5 1.5 28th 50.2 29.4 high 171%
Central Coast (district 09)
Badgingarra Research Stn 20.6 0.0 29.2 16th 8.0 +0.5 2.8 28th 73.2 51.4 high 142%
Bickley 18.1 +0.7 25.9 9th 8.2 0.0 3.7 28th 207.8 123.6 high 168%
Champion Lakes 20.4   27.8 9th 10.6   3.6 28th 107.4
Garden Island HSF 19.4 +0.6 27.8 16th 12.4 +0.6 6.7 28th 66.2 60.4 average 110%
Gingin Aero 21.6 +1.2 29.7 9th 7.8 +0.5 1.7 24th 82.4 84.4 average 98%
Gosnells City 21.8 +1.1 30.2 9th 10.7 +0.7 3.3 28th 105.5 81.7 high 129%
Jandakot Aero 21.1 +1.2 29.1 9th 8.4 +0.3 1.0 28th 114.2 86.2 high 132%
Jurien Bay 22.6 +1.4 31.1 30th 10.8 +0.9 4.2 29th 55.2 44.6 average 124%
Karnet 18.1 +0.6 26.5 9th 7.6 +0.4 -0.6 28th 219.4 131.7 v high 167%
Lancelin 22.4 +2.0 31.0 16th 10.4 -0.1 6.5 24th 49.4 56.0 average 88%
Medina Research Centre 21.2 +1.0 28.9 9th 10.0 +0.9 2.7 29th 69.0 76.3 average 90%
Pearce RAAF 21.5 +1.5 28.7 9th 8.8 +0.1 2.9 24th 74.2 68.8 average 108%
Perth Airport 21.4 +1.3 29.5 9th 8.8 -0.1 1.9 28th 103.6 72.2 high 143%
Perth Metro* 21.5 +1.4 29.3 9th 9.8 +0.4 3.8 28th 90.8 80.8 average 112%
Rottnest Island 19.4 +0.7 24.0 9th 13.1 +0.3 8.9 28th 48.0 52.7 average 91%
Swanbourne 21.4 +1.7 29.2 16th 11.1 +0.2 5.3 28th 90.8 81.0 average 112%
South Coast (district 09A)
Albany 18.4 +1.2 23.1 30th 10.1 +0.9 6.1 22nd 148.2 101.7 high 146%
Albany Airport 18.4   24.0 30th 8.0   3.0 24th 139.6
Albany Airport Comparison 18.2 +0.9 24.0 30th 8.3 +0.3 3.3 24th 134.2 87.2 v high 154%
Bridgetown 18.2 +0.7 24.8 17th 6.3 +0.4 0.6 13th 131.4 96.2 high 137%
Bunbury 19.3 +1.0 24.8 17th 8.1 -0.3 1.6 23rd 106.6 80.7 high 132%
Busselton Aero 19.2 +1.0 24.9 16th 7.5 -0.1 1.6 28th 93.0 81.7 average 114%
Cape Leeuwin 18.1 +1.0 22.1 8th 12.4 +0.6 8.4 5th 82.8 90.9 average 91%
Cape Naturaliste 18.7 +1.4 23.2 16th 10.6 +0.2 6.2 28th 106.0 76.5 high 139%
Collie East 18.9   26.1 9th 5.3   -0.4 28th 131.2 89.3 high 147%
Donnybrook 19.7 +0.9 27.0 17th 7.7 +0.6 2.0 28th 163.0 102.4 high 159%
Dwellingup 18.3 +1.1 26.1 9th 6.8 +0.4 -0.6 28th 237.6 131.0 v high 181%
Esperance 21.1 +1.8 32.8 10th 9.9 +0.4 6.4 8th 69.2 61.7 average 112%
Esperance Aero 20.2 +1.5 30.0 10th 8.7 +0.4 4.4 23rd 48.0 57.7 average 83%
Harvey 19.6 +1.1 25.5 9th 8.1 -0.3 2.0 29th 131.0 113.9 average 115%
Hopetoun North 20.7 +0.4 29.7 10th 7.3 -1.4 1.8 15th 44.6 50.5 average 88%
Jarrahwood 19.3 +1.3 26.0 17th 5.9 -0.1 -0.5 13th        
Mandurah 19.8 +1.0 28.2 16th 12.0 +0.4 6.2 28th 92.4 64.9 high 142%
Manjimup 18.1 +1.6 25.9 9th 7.7 +0.5 3.7 13th 116.0 109.2 average 106%
North Walpole 18.1   24.2 17th 9.1   4.5 24th
Pemberton 18.3 +1.6 24.6 9th 8.4 +0.8 3.9 24th 181.1 128.9 high 140%
Rocky Gully 17.6 +1.3 23.8 9th 7.2 +0.2 1.9 13th 124.2 95.0 high 131%
Windy Harbour 18.1 +0.5 24.3 9th 9.4 0.0 4.6 8th 151.2 110.1 high 137%
Witchcliffe 18.2 +0.9 23.9 17th 8.5 -0.1 2.9 24th 164.6 116.9 high 141%
North Central (district 10)
Bencubbin 21.9 +1.0 28.9 16th 8.4 +1.3 1.5 28th 35.0 21.9 high 160%
Cunderdin Airfield 22.3 +1.8 29.6 30th 5.3 +0.6 -0.2 28th 23.2 26.1 low 89%
Kellerberrin 22.2 +1.5 29.0 17th 5.3 -1.1 -0.5 28th 23.6 26.0 average 91%
Merredin 22.2 +1.8 30.5 17th 8.1 +1.4 0.0 28th 34.9 25.8 high 135%
Northam 21.6 +1.2 29.3 16th 6.2 -0.6 -0.5 28th 49.4 37.2 high 133%
York 21.3 +1.4 28.7 30th 3.6 -1.2 -1.3 28th 56.5 38.5 high 147%
South Central (district 10A)
Beverley 21.8 +1.6 29.6 16th 5.1 -0.7 -0.2 28th 49.1 36.1 high 136%
Brookton 20.3 +1.2 27.7 17th 5.2 -0.1 0.1 28th 64.7 38.4 high 168%
Corrigin 21.0 +1.9 28.9 17th 6.0 +0.3 -0.5 29th 25.4 29.7 average 86%
Hyden 22.4 +2.1 30.7 17th 6.2 +0.4 -0.4 23rd 21.3 27.7 average 77%
Jacup 20.3 +1.7 27.7 9th 6.1 -0.1 -0.1 23rd 47.2 47.4 average 100%
Katanning 18.4 +1.1 26.3 17th 6.1 +0.1 -0.1 23rd 71.6 51.6 high 139%
Lake Grace 20.7 +1.7 28.9 17th 6.6 +0.3 1.1 23rd 26.8 28.3 average 95%
Narembeen 22.1 +1.7 30.1 17th 6.9 +0.8 0.9 28th 26.8 25.7 average 104%
Narrogin 19.1 +1.4 27.4 17th 6.1 +0.1 1.0 29th 79.4 46.4 v high 171%
Newdegate Research Station 20.8 +2.2 28.6 17th 4.7 -0.1 -2.0 23rd 21.6 33.9 average 64%
Ongerup 19.4 +1.6 26.2 17th 6.9 +0.4 0.4 23rd 44.6 38.2 average 117%
Pingelly 20.1 +1.8 27.2 17th 6.3 -0.1 1.4 28th 62.0 40.6 high 153%
Ravensthorpe 21.2 +1.8 29.9 10th 7.8 +0.4 1.3 23rd 25.5 41.4 low 62%
Wagin 19.3 +1.2 28.1 17th 6.2 +0.1 0.3 23rd 55.4 41.2 high 134%
Wandering 18.6 +0.4 26.3 17th 4.1 -0.6 -1.0 28th 89.0 56.6 high 157%
Eucla (district 11)
Balladonia 23.8 +1.5 33.0 10th 7.5 +0.7 2.5 24th 12.4 20.0 average 62%
Eucla 24.0 +2.7 36.8 25th 9.5 +0.4 2.1 14th 2.0 22.4 v low 9%
Eyre 24.1 +3.0 35.6 25th 6.8 -0.9 -2.5 30th 8.2 23.6 low 35%
Forrest 26.3 +2.1 37.2 25th 8.2 0.0 3.1 14th 1.2 16.2 low 7%
Red Rocks Point 23.4   37.1 25th 10.0   4.6 9th 11.2
South East (district 12)
Bulga Downs 26.1   33.3 10th 9.3   3.6 5th 5.4 7.7 average 70%
Kalgoorlie-Boulder Airport 23.3 +1.1 31.1 10th 9.4 +1.4 2.6 28th 12.8 14.1 average 91%
Laverton Aero 26.2 +1.9 32.5 3rd 10.7 +0.4 5.1 5th 1.6 7.7 low 21%
Leinster Aero 26.6 +1.2 33.9 17th 11.2 +0.7 4.6 29th 1.6 3.9 average 41%
Leonora 26.2 +1.4 32.7 10th 10.4 +0.4 5.1 28th 3.8 8.9 average 43%
Leonora Aero 26.1   32.1 17th 10.2   4.1 9th 2.2
Munglinup West 21.4 +1.7 31.6 10th 7.6 +0.4 2.6 28th 27.6 37.7 average 73%
Norseman Aero 23.0 +0.8 31.9 10th 6.6 +0.4 -0.4 13th 7.6 22.4 v low 34%
Salmon Gums Res.Stn. 22.2 +1.9 31.9 10th 6.2 +0.5 0.2 13th 25.6 31.7 average 81%
Southern Cross Airfield 22.7 +1.3 31.8 10th 6.6 +1.6 -1.3 28th 17.4 21.7 average 80%
Yeelirrie 27.5 +1.8 33.7 15th 9.1 +1.3 1.5 9th 0 4.6 lowest 0%
North East (district 13)
Balgo Hills         19.7 +1.1 14.3 10th 0 3.1 lowest 0%
Carnegie 30.6 +2.2 36.5 18th 12.0 +0.5 4.3 6th 0 3.9 lowest 0%
Giles Meteorological Office 30.1 +2.7 36.6 26th 14.3 +1.4 5.8 8th 0.4 11.1 low 4%
Telfer Aero 35.2 +2.5 39.5 26th 18.4 +2.0 12.7 6th 0 2.5 lowest 0%
Warburton Airfield 30.2 +2.4 36.4 18th 11.9 +0.7 2.3 6th 0.2 5.7 average 4%
Wiluna 28.2 +1.9 35.0 16th 10.9 +1.0 3.5 29th 1.0 4.6 average 22%
Offshore Islands (district 200)
Christmas Island Aero 26.5 +0.3 27.3 12th 22.3 +0.1 21.2 7th 3.6 44.8 v low 8%
Cocos Island Airport 28.3 +0.1 28.8 19th 23.9 0.0 20.9 23rd 34.8 93.4 average 37%
Varanus Island 27.3 +0.5 29.3 16th 21.1 +0.4 18.8 5th 0 0.4 v low 0%

Notes

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 2 October 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 decile ranking (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.

*Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Mt Lawley site, the most significant changes of this kind relate to minimum temperature and rain days.

For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Mt Lawley site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

For PDF files of Perth Metro climate statistics for other months, please click here for extremes and here for averages.

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