Western Australia in September 2018: driest September in decades

Rainfall in September 2018 was below to very much below average in the southwest, northeast, and southeast parts of Western Australia. It was the third-driest September and driest in eight decades since 1939 for the State as a whole. For the South West Land Division, it was the fourth-driest start to spring and driest since 1939. The mean maximum temperatures were above average across most of the State whilst the mean minimum temperatures were generally near average except the southwest where the overnight temperatures were below average.

Below average rainfall across most of WA

  • For Western Australia as a whole, rainfall in September 2018 was the third-lowest in September on record, and driest in eight decades since 1939
  • For South West Land Division (SWLD) as a whole, it was the fourth-driest September on record, and driest in eight decades since 1939
  • Rainfall totals were mostly less than 10 mm in the Gascoyne, Goldfields and Eucla districts, and the north and east of the SWLD apart from its coastal areas
  • A dozen sites in the SWLD had their driest September on record
  • Many sites recorded their lowest September rainfall for at least 20 years
  • Rainfall at the end of month was the only useful falls in the southern Goldfields districts

Above average maximum temperatures for most of WA

  • Daytime temperatures were above average for most of the State; the mean maximum temperature was 1.6 °C above average for WA as a whole
  • Mean minimum temperature was close to average for WA, however, the mean minimum temperature was one degree below average for the SWLD
  • Sunny and easterly winds saw warmer than normal daytime temperatures across most of WA between the 23rd and 26th, and 40.9 °C recorded at Roebourne Aero in the Pilbara on the 26th was the highest temperature of the month in the country
  • Clear skies and light winds led to two consecutive very cold mornings in the SWLD on the 15th and 16th, with a number of sites broke their lowest September temperature record
  • Fresh easterly winds resulted in daily minimum temperatures in the high 10s in the Central West district on the 29th, and Morawa Airport had its highest daily minimum temperature on record

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Extremes in September 2018
Hottest day 40.9 °C at Roebourne Aero on the 26th
Warmest days on average 38.4 °C at Wyndham Aero
Coolest days on average 16.1 °C at Shannon
Coldest day 10.4 °C at Rocky Gully on the 14th
Coldest night -4.6 °C at Eyre on the 7th
Coolest nights on average 3.1 °C at York
Warmest nights on average 25.1 °C at Troughton Island
Warmest night 26.4 °C at Argyle Aerodrome on the 19th
Warmest on average overall 30.0 °C at Argyle Aerodrome
Coolest on average overall 11.1 °C at Wandering
Wettest overall 89.2 mm at Wereroa
Wettest day 23.0 mm at Walpole Forestry on the 5th
Strongest wind gust 100 km/h at Cape Leeuwin 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

Click on a map to show it full size in a pop-up window


Record lowest September total rainfall
New record
(mm)
Old
record
Years of
record
Average for
September
Hyden 3.0 4.6 in 1954 89 27.8
Bodallin South 3.0 5.2 in 2015 84 25.2
King Rocks 1.8 4.4 in 1980 80 26.6
Jourerdine 1.7 3.5 in 1939 70 20.0
Rocky Gully Town 18.6 22.6 in 1954 65 77.8
Amrista Park 2.0 7.0 in 1980 62 29.2
Jandakot Aero 28.6 31.8 in 1977 44 85.4
Dwarda Downs 9.2 13.2 in 2010 37 56.3
Nunile 9.2 10.0 in 2015 28 45.0
Perth Metro 35.2 = 35.2 in 2004 26 84.8
Gingin Aero 16.0 23.2 in 2000 23 80.3

Lowest September total rainfall for at least 20 years
Observed
(mm)
Most recent
lower
Average for
September
Pingelly 5.7 2.6 in 1916 40.8
Walebing 4.6 2.5 in 1916* 44.0
Doodlakine 3.8 2.1 in 1929* 22.3
Marradong 16.6 10.9 in 1939 71.8
Northam 6.9 2.6 in 1939 37.1
Wattening 8.8 3.3 in 1939 35.7
Colorado 4.2 0.0 in 1939* 30.2
Salmon Gums Res.Stn. 3.0 2.5 in 1939* 31.9
Pingaring 3.6 2.5 in 1939* 27.9
Cowaramup 42.0 39.7 in 1967 111.4
Manjimup 45.2 37.6 in 1969 108.2
Pearce RAAF 20.4 7.7 in 1969 68.8
Windrush 30.4 28.2 in 1969 75.1
Boscabel 15.0 13.5 in 1969* 52.3
Wialki South 1.6 0.0 in 1967* 20.7
Bakers Hill 14.6 11.9 in 1969* 62.1
Riverdale 16.2 =16.2 in 1972* 49.5
Cape Leeuwin 35.6 31.7 in 1974 90.4
Nabawa 7.4 4.3 in 1977 36.0
Ygnattering 5.5 4.2 in 1977 24.2
Yuna 4.2 2.6 in 1977 24.0
Dandaragan West 19.0 12.4 in 1977* 56.8
Roleystone 41.7 40.4 in 1974* 112.3
Bullfinch 3.0 2.0 in 1980 19.6
Bungulla 5.4 3.2 in 1980 23.2
Goodlands 4.4 2.2 in 1980 21.2
Nangeenan 2.4 2.2 in 1980 24.6
Ravensthorpe 8.2 3.2 in 1980 42.0
Ardath 3.6 3.0 in 1980* 24.8
Bonnie Rock 2.8 2.6 in 1980* 18.5
Hines Hill 2.8 2.6 in 1980* 20.7
Lynton 5.0 4.8 in 1977* 26.6
Maida Vale 46.3 28.2 in 1977* 87.3
Latham 6.2 5.6 in 1989 19.2
Warra Jarra 14.2 14.0 in 1989* 48.2
Frankland 20.0 12.8 in 1969* 64.7
Mukinbudin 6.6 5.2 in 1989* 18.6
Windy Harbour 52.0 47.8 in 1994* 113.8
Wubin 9.0 5.0 in 1989* 20.1

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




Record highest September daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Morawa Airport 17.3 on the 29th 17.1 on the 29th in 2010 22 7.7



Record lowest September temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Ongerup -2.2 on the 15th -0.5 on the 13th in 1978 52 6.5
Hyden -2.4 on the 15th -2.0 on the 22nd in 2008 46 5.9
Wagin -1.5 on the 15th -1.4 on the 29th in 2016 44 6.2
Jarrahwood -2.7 on the 15th -2.1 on the 29th in 2016 37 6.0
Newdegate Research Station -4.3 on the 15th -3.7 on the 11th in 2004 23 4.8
Rocky Gully 0.1 on the 16th 0.3 on the 22nd in 2004 23 7.1



Summary statistics for September 2018
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
September
2018
Diff
from
average
Highest for
September
2018
Mean for
September
2018
Diff
from
average
Lowest for
September
2018
Total for
September
2018
Average
for
September
Rank of
September
2018
Fraction of
September
average
North Kimberley (district 01)
Kalumburu 37.2 +1.3 40.0 24th 18.7 -0.4 15.6 24th 0 1.6 lowest 0%
Troughton Island 30.7 +0.4 32.4 22nd 25.1 +0.5 23.8 1st 0 0.3 lowest 0%
Truscott 33.4 -0.1 36.6 23rd 22.3 +0.4 19.9 13th 0 0.2 v low 0%
Wyndham Aero 38.4 +0.6 40.0 7th 21.3 -0.2 15.7 23rd 0 3.6 lowest 0%
East Kimberley (district 02)
Argyle Aerodrome 37.4 +0.9 39.1 19th 22.6 +0.3 18.3 13th 0 2.3 lowest 0%
Halls Creek Airport 35.7   37.3 29th 17.3   11.7 13th 2.4
Kununurra Aero 37.9 +1.2 39.7 15th 18.5 -1.4 12.9 12th 0 4.1 lowest 0%
Warmun 35.3 -0.9 35.8 18th 17.5 -1.8 10.6 12th 0 4.3 lowest 0%
West Kimberley (district 03)
Broome Airport 33.1 +1.3 39.0 25th 17.4 -1.1 11.7 1st 0.6 1.4 average 43%
Curtin Aero 37.4 +0.8 39.7 11th 17.9 -0.4 12.1 1st 0 0.1 lowest 0%
Cygnet Bay       17.6 -0.2 13.2 1st 0 1.2 lowest 0%
Derby Aero 36.5 +1.0 39.9 16th 18.2 -1.2 14.1 1st 0 1.0 lowest 0%
Fitzroy Crossing Aero 38.2 +0.8 40.2 4th 18.2 -0.3 12.7 1st 0 0.3 lowest 0%
De Grey (district 04)
Bedout Island 28.8 +0.1 32.1 25th 21.7 -0.5 19.2 1st
Karratha Aero 32.0 +1.2 37.7 24th 17.2 +0.2 13.4 7th 0 1.3 lowest 0%
Legendre Island 28.6   34.9 24th 20.1   18.2 7th
Mandora 35.4 +1.6 39.5 25th 15.2 -0.5 8.7 1st 0.6 1.0 high 60%
Marble Bar 35.4 +0.7 40.1 26th 17.2 +0.5 10.8 1st 0 3.9 v low 0%
Port Hedland Airport 34.6 +2.2 40.0 25th 16.1 +0.6 11.0 1st 0 1.2 lowest 0%
Roebourne Aero 34.8 +1.5 40.9 26th 15.3 -0.1 10.4 7th 0 2.1 v low 0%
Fortescue (district 05)
Barrow Island Airport 27.6 +0.6 32.0 25th 19.3 -0.2 16.8 1st 0 1.2 lowest 0%
Karijini North 32.6   37.5 26th 17.2   10.5 2nd 0
Learmonth Airport 30.7 +1.3 36.5 24th 13.4 -0.4 10.1 3rd 0 2.1 lowest 0%
Mardie     38.0 23rd 14.6 +0.2 10.8 1st 0 1.3 lowest 0%
Onslow Airport 31.4 +1.3 38.2 24th 16.6 +1.2 13.4 7th 0.2 1.4 average 14%
Thevenard Island 28.1 +0.5 35.4 24th 18.9 +0.3 15.7 20th 0.4 1.2 low 33%
Wittenoom 33.0 +1.7 37.7 26th 17.8 +0.9 10.8 1st 0 2.9 lowest 0%
West Gascoyne (district 06)
Carnarvon Airport 25.4 +0.9 33.4 22nd 13.2 -0.7 9.3 22nd 4.2 6.1 average 69%
Denham 23.6 -0.3 31.5 22nd 14.1 -0.8 11.0 12th 4.0 8.1 average 49%
Murchison 27.0 +0.8 34.4 28th 9.6 0.0 4.9 7th 0 8.3 lowest 0%
Shark Bay Airport 25.9 0.0 33.5 22nd 11.9 -0.8 8.9 22nd 6.8 9.6 average 71%
East Gascoyne (district 07)
Newman Aero 31.2 +0.8 37.5 26th 12.9 +0.8 6.5 21st 0 3.8 lowest 0%
Paraburdoo Aero 32.1 +0.8 37.0 26th 13.3 -0.3 7.4 7th 0 3.4 lowest 0%
Murchison (district 07A)
Meekatharra Airport 27.5 +1.8 33.8 26th 11.9 +0.4 6.0 6th 0 4.4 lowest 0%
Mount Magnet Aero 25.6 +1.0 33.2 24th 10.4 +0.1 5.5 7th 2.8 10.0 low 28%
Paynes Find 24.5 +0.7 32.4 22nd 7.5 -0.6 2.1 12th 1.4 14.2 v low 10%
North Coast (district 08)
Dalwallinu 21.4 +0.4 30.3 22nd 6.5 -0.4 0.6 15th 6.0 24.7 v low 24%
Geraldton Airport 23.1   33.1 28th 7.2   2.4 12th 4.6
Kalbarri 24.4 +0.4 35.2 28th 10.6 -0.2 4.7 9th 15.6 23.9 average 65%
Morawa Airport 23.8 +0.7 32.0 22nd 6.9 -0.8 2.5 16th 2.6 22.8 v low 11%
Mullewa 24.2 +0.7 31.7 22nd 8.7 +0.1 3.8 7th 5.4 21.6 low 25%
North Island 22.0 -0.1 25.1 20th 15.7 -0.2 10.1 23rd 3.6 19.5 v low 18%
Wongan Hills 21.3 +0.6 29.5 23rd 6.7 -0.9 2.5 15th 11.0 29.6 low 37%
Central Coast (district 09)
Badgingarra Research Stn 19.7 -0.8 27.2 23rd 6.5 -1.1 2.7 13th 4.0 49.3 v low 8%
Bickley 17.7 +0.2 25.5 22nd 7.7 -0.5 1.4 15th 46.6 124.3 v low 37%
Garden Island HSF 18.1 -0.8 23.2 22nd 11.2 -0.7 6.9 15th 21.4 65.0 v low 33%
Gingin Aero 21.1 +0.5 29.3 22nd 6.5 -1.0 0.3 16th 16.0 80.3 lowest 20%
Jandakot Aero 20.1 0.0 27.5 22nd 7.3 -0.9 1.9 16th 28.6 85.4 lowest 33%
Jurien Bay 21.9 +0.6 29.4 29th 9.5 -0.5 2.9 16th 12.8 44.3 v low 29%
Lancelin 20.4 -0.1 27.5 29th 9.8 -0.8 3.5 16th 31.2 57.0 low 55%
Millendon (Swan Valley) 20.9   28.7 22nd 7.4   1.6 16th 27.4
Pearce RAAF 20.7 +0.6 27.9 23rd 7.8 -1.0 2.5 16th 20.4 68.8 v low 30%
Perth Airport 20.6 +0.4 28.2 22nd 8.1 -0.8 2.6 16th 37.6 72.7 low 52%
Perth Metro 20.5 +0.2 28.0 22nd 8.8 -0.8 2.8 16th 35.2 84.8 lowest 42%
Rottnest Island 18.5 -0.3 23.3 23rd 12.4 -0.5 8.3 15th 18.8 54.6 v low 34%
Swanbourne 19.3 -0.6 25.9 22nd 10.4 -0.6 6.0 15th 37.2 81.5 low 46%
South Coast (district 09A)
Albany 17.0 -0.3 24.8 20th 10.3 +1.0 4.9 16th 65.3 101.7 low 64%
Albany Airport 17.8   24.2 20th 8.4   2.4 16th 44.4
Bridgetown 17.8 +0.2 24.5 23rd 5.9 -0.1 -1.7 15th 11.2 88.1 v low 13%
Bunbury 18.6 +0.1 24.4 30th 7.2 -1.3 1.8 15th 29.2 81.3 v low 36%
Busselton Aero 18.1 -0.2 25.6 23rd 7.5 -0.2 1.1 15th 28.0 75.1 low 37%
Cape Leeuwin 17.1 0.0 20.7 22nd 12.2 +0.4 7.5 15th 35.6 90.4 v low 39%
Cape Naturaliste 17.9 +0.5 22.1 30th 10.2 -0.2 4.1 15th 26.4 75.9 v low 35%
Collie East 18.5 +0.2 26.1 23rd 4.8 -0.7 -2.2 15th 36.2 90.5 low 40%
Donnybrook 19.4 +0.6 27.4 23rd 6.7 -0.4 1.0 15th 29.4 102.3 v low 29%
Dwellingup 17.6 +0.3 25.0 23rd 5.8 -0.7 -0.1 15th 59.8 130.6 low 46%
Esperance 19.2 -0.2 25.2 3rd 9.5 0.0 5.2 29th 38.0 61.5 low 62%
Esperance Aero 19.2 +0.3 29.3 23rd 8.0 -0.4 3.8 15th 46.6 58.6 average 80%
Hopetoun North 19.4 -0.6 25.9 16th 9.1 +0.6 2.9 16th 18.4 50.4 v low 37%
Jarrahwood 18.7 +0.5 27.0 23rd 5.3 -0.7 -2.7 15th 46.8 104.6 v low 45%
Mandurah 18.9 -0.1 24.2 22nd 10.9 -0.8 5.9 15th 18.2 64.2 v low 28%
Manjimup 17.1 +0.5 24.3 23rd 7.4 +0.2 1.7 15th 45.2 108.2 v low 42%
North Walpole 17.0 -0.3 22.3 20th 9.2 0.0 3.6 16th 67.2 113.5 low 59%
Rocky Gully 16.7 +0.2 23.8 23rd 7.1 0.0 0.1 16th 37.4 95.3 v low 39%
Shannon 16.1 -0.3 22.9 23rd 7.2 -0.1 1.0 16th 62.6 111.5 low 56%
Witchcliffe 16.9 -0.5 21.9 23rd 8.6 0.0 1.7 15th 36.8 110.7 v low 33%
North Central (district 10)
Bencubbin 20.6 -0.4 31.0 24th 6.5 -0.7 1.2 15th 8.7 21.8 low 40%
Cunderdin Airfield 21.7 +0.9 30.2 23rd 4.0 -0.9 -1.9 15th 6.6 26.2 low 25%
Northam     26.2 30th 5.7 -1.1 1.3 15th 6.9 37.1 v low 19%
York 21.1 +0.9 29.0 22nd 3.1 -1.7 -2.0 16th 13.1 38.1 low 34%
South Central (district 10A)
Beverley 21.3 +1.0 28.8 23rd 4.9 -0.9 -1.4 16th 7.2 36.1 v low 20%
Brookton 19.8 +0.6 28.0 22nd 3.8 -1.6 -1.5 16th 10.6 38.6 v low 27%
Corrigin 20.1 +0.9 29.5 22nd 5.3 -0.5 -0.3 15th 3.1 29.6 lowest 10%
Hyden 21.4 +1.0 31.1 22nd 5.3 -0.6 -2.4 15th 3.0 27.8 lowest 11%
Jacup 19.7 +0.9 30.1 24th 5.5 -0.7 -0.3 15th 11.4 43.9 v low 26%
Katanning 17.7 +0.2 25.1 22nd 5.9 -0.2 -0.8 15th 12.0 51.7 v low 23%
Lake Grace 19.8 +0.6 28.6 23rd 5.9 -0.6 -1.8 15th 6.6 27.8 low 24%
Narembeen 21.5 +1.0 30.8 22nd 5.6 -0.6 -0.4 15th 14.8 26.1 low 57%
Narrogin 18.5 +0.8 27.0 22nd 5.6 -0.4 -1.6 15th 18.0 46.4 low 39%
Newdegate Research Station 19.8 +1.0 29.1 23rd 4.0 -0.8 -4.3 15th 6.6 33.1 v low 20%
Pingelly 19.5 +1.1 27.0 22nd 5.9 -0.6 0.8 16th 5.7 40.8 v low 14%
Ravensthorpe 20.6 +1.1 31.5 23rd 7.2 -0.2 2.0 14th 8.2 42.0 v low 20%
Wagin 18.4 +0.2 27.0 22nd 6.0 -0.2 -1.5 15th 13.9 41.1 v low 34%
Wandering 18.6 +0.3 26.3 23rd 3.6 -1.2 -2.3 15th 19.6 59.1 low 33%
Eucla (district 11)
Balladonia 22.1 -0.2 34.0 24th 5.9 -0.9 0.7 7th 9.0 19.6 low 46%
Eucla 23.6 +2.3 34.2 10th 9.0 -0.1 1.1 16th 2.4 22.1 v low 11%
Eyre 23.8 +2.5 36.1 24th 6.6 -1.1 -4.6 7th 10.8 23.6 low 46%
Forrest 25.4 +1.0 34.5 25th 6.5 -1.7 0.0 16th 0 14.8 lowest 0%
Red Rocks Point 22.9 +1.6 34.4 10th 9.4 -0.5 2.8 7th 1.8 27.1 v low 7%
South East (district 12)
Bulga Downs 26.1 +0.8 33.8 24th 9.0 +0.2 2.2 7th
Kalgoorlie-Boulder Airport 23.3 +1.0 33.8 24th 8.7 +0.7 1.2 15th 2.8 13.9 low 20%
Laverton Aero 25.3 +0.8 34.7 24th 10.3 -0.1 3.2 7th 2.4 7.3 average 33%
Leinster Aero 26.4 +0.9 34.7 24th 10.2 -0.4 3.1 7th 2.4 3.9 average 62%
Leonora Aero 25.8 +0.8 34.8 24th 9.4 -0.7 2.5 7th 3.6 7.3 average 49%
Munglinup West 20.6 +0.7 32.5 23rd 6.5 -0.8 1.4 15th 8.6 39.2 v low 22%
Norseman Aero 23.0 +0.7 34.4 24th 5.5 -0.8 -3.5 15th 0.4 21.2 v low 2%
Salmon Gums Res.Stn. 21.2 +0.8 33.0 23rd 5.0 -0.7 -1.9 15th 3.0 31.9 v low 9%
Southern Cross Airfield 22.7 +1.1 32.1 23rd 4.6 -0.8 -0.7 6th 3.0 21.2 v low 14%
North East (district 13)
Carnegie 29.4 +0.7 36.8 26th 11.4 -0.1 2.0 16th 0 3.6 lowest 0%
Giles Meteorological Office 28.4 +0.9 36.3 30th 13.0 0.0 5.7 16th 0.4 10.2 low 4%
Telfer Aero 33.9 +1.0 38.5 27th 16.2 -0.3 9.4 1st 0 2.1 lowest 0%
Warburton Airfield 29.0 +1.0 35.6 26th 11.7 +0.4 3.2 8th 0 5.4 lowest 0%
Wiluna 27.7 +1.4 35.0 24th 9.7 -0.2 3.0 7th 10.0 5.0 high 200%
Wiluna Aero 28.1   35.5 24th 10.4   2.6 7th 0.6
Offshore Islands (district 200)
Adele Island 28.7   30.5 20th     22.6 8th
Rowley Shoals 26.5   29.4 29th     23.3 14th

Notes

The Monthly climate summary, generally published on the first working day of each month, lists 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. More extensive discussion of significant weather events, along with later information and data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review.

This statement has been prepared based on information available at 11 am on Monday 1 October 2018. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

In some situations, some or all of the rainfall is in the form of hail or snow. In these cases the totals given are for the water equivalent: the depth of liquid water that results from melting any frozen precipitation. There can be significant 'undercatch' of snow in strong winds, meaning the true precipitation can be higher than that reported.

Averages for individual sites 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 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.

Where temperature area averages are mentioned, they are derived from the ACORN-SAT dataset.

Further information

Media
(03) 9669 4057
Enquiries