Western Australia in May 2011: A dry month in WA

  • Rainfall: Below average for both WA and southwest WA;
  • Maximum temperature: Below average for WA; but above average for southwest WA.
  • Minimum temperature: Below average for WA; near average for southwest WA.

Rainfall

May 2011 rainfall was below average in the eastern Kimberley, eastern Interior, northern Goldfields and eastern Gascoyne. Parts of the Southwest Land Division (SWLD) also observed below average rainfall, with an area of very much below average observed in parts of the Southwest district and adjacent parts of the Great Southern. Above average rainfall was confined to patches in the central Pilbara, Western Gascoyne, northern Central west, western South Coastal and coastal Eucla (see May 2011 rainfall totals & deciles).

When averaged across the state, rainfall during May 2011 was below average for both WA and the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay).

A cloudband produced moderate to heavy rainfall in the Pilbara, Gascoyne and northern Central West on the 16th, with Karratha Airport recording daily rainfall total of 77.0 mm, exceeding its previous May record of 74.0 mm set on the 22 May 1972. Hines Hill in the Central Wheat Belt broke its May daily rainfall record on the 18th due to thunderstorms ahead of a cold front moving through the SWLD while

A cold front brought the first significant season rainfall to the Lower Southwest on the 20th, with daily rainfall totals mostly in the 20 mm to 50 mm range in the Lower West and Southwest districts, grading to around 10 to 20 mm in the Central West and Central Wheatbelt. Donnybrook in the Southwest observed a daily rainfall total of 52.0 mm on the 20th, while Tamaru in the South Coastal broke its highest May daily rainfall with 54.6 mm in the 24 hours to 9am on the 21st.

A strong cold front moved through the SWLD and adjacent Gascoyne late on the 29th and during the 30th with a number of heavy falls observed. 24 hour rainfall totals to 9am on the 30th were generally between 25 and 50 mm along the west coast and adjacent inland areas from Shark Bay to Busselton, with isolated heavier falls in the 50 to 70 mm range. Mandurah in the Lower West observed 28.0 mm in 60 mins (2117 WST to 2217 WST), which has an Average Return Interval (ARI) of between 10 to 20 years. Nabawa in the Central West recorded the highest 24 hour total with 64.0 mm in the 24 hours to 9am on the 30th.

Maximum temperature

May 2011 maximum temperature was below to very much below average over a large area from central to eastern WA, with areas of lowest on record in the central and western Pilbara, northwest Interior, eastern Kimberley and eastern Eucla. Mean maxima was up to 3 °C cooler than normal in those areas, with a patch of up to 4 °C cooler than normal in the northwest Interior and far east inland Pilbara. In contrast, above average mean maxima were observed over much of the SWLD and adjacent western Gascoyne, with an area of very much above average in the western Lower West and western Southwest districts where mean maxima was with up to 2 °C warmer than normal (see May 2011 mean maximum temperature decile & anomaly maps).

When averaged across the state as a whole, mean maximum temperature during May 2011 was below average; however, the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) observed above average mean maximum temperature. Comparable records began in 1950.

Minimum temperature

Mean minimum temperature during May 2011 was below to very much below average in most of the northern half of WA, with up to 4 °C cooler than normal mean minima in the eastern Kimberley. Above average to very much above average overnight temperatures were observed in the Eucla, southern Goldfields and eastern parts of the SWLD (see May 2011 minimum temperature decile & anomaly maps).

When averaged across the state as a whole, mean minimum temperature during May 2011 was below average, whilst the Lower Southwest (southwest of a line from Jurien Bay to Bremer Bay) observed near average mean minima.

Other Phenomena

Waterspouts were reported offshore from Yallingup in the afternoon of the 4th, with a narrow convergence line was located off the southwest Capes. The Perth (Serpentine) radar showed strong reflectivities in the low levels.

A low off the Pilbara coast combined with ridging over central Australia to produce strong to gale force easterly winds over coastal parts of the Pilbara. Varanus Island observed a severe wind gust of 91 km/h at 1748 WST on the 4th.

A cold front crossed the SWLD during the morning of the 20th with roof and powerline damage reported in Canning Vale around 0800 WST. Severe wind gusts were observed at Rottnest Island from 1200 to 1300 WST, and a maximum wind gust of 96 km/h was observed at 1235 WST High tides, well above the Highest Astronomical Tide (HAT), were observed at Bunbury (1.63 m), Busselton (1.88 m), Fremantle (1.88 m), Barrack Street (1.73 m), and Geraldton (1.45 m).

The passage of a cold front across the southwest corner was accompanied by a tornado in Bunbury at around 0900 WST on the 29th with house and tree damage confined two streets in the Bunbury suburb of Usher.

Further information

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Extremes in May 2011
Hottest day 35.1 °C at Wyndham Aero on the 3rd
Warmest days on average 31.6 °C at West Roebuck
Coolest days on average 18.6 °C at Shannon
Coldest day 14.0 °C at Shannon on the 20th
Coldest night -2.4 °C at Eyre on the 28th
Coolest nights on average 6.0 °C at Jarrahwood
Warmest nights on average 24.5 °C at Troughton Island
19.0 °C at Truscott(mainland)
Warmest night 27.1 °C at Troughton Island on the 10th
23.5 °C at Bidyadanga on the 6th (mainland)
Wettest overall 138.1 mm at Northcliffe
Wettest day 77.0 mm at Karratha Aero on the 16th
Highest wind gust 106 km/h at Cape Leeuwin on the 29th

Record highest May daily rainfall
Highest daily rainfall
in May 2011 (mm)
Previous wettest
for May
Years of
record
Hines Hill 51.6 on the 18th 40.6 on the 5th in 1965 78
Tamaru 54.6 on the 21st 49.5 on the 15th in 1986 46
Karratha Aero 77.0 on the 16th 74.9 on the 22nd in 1973 39



Summary statistics for May 2011
Maximum temperatures
for May
(°C)
Minimum temperatures
for May
(°C)
Rainfall
for May
(millimetres)
Mean for
May
2011
Diff
from
average
Highest for
May
2011
Mean for
May
2011
Diff
from
average
Lowest for
May
2011
Total for
May
2011
Average
for
May
Rank of
May
2011
Fraction of
May
average
North Kimberley (district 01)
Doongan 28.9 -2.4 31.5 22nd 12.4 -2.4 5.9 29th 0 12.0 v low 0%
Kalumburu 31.5 -2.0 34.6 3rd 14.8 -2.1 8.9 30th 0 19.5 v low 0%
Mount Elizabeth 28.4 -1.6 31.5 1st 10.8 -1.4 4.1 28th 5.0 13.9 average 36%
Troughton Island 29.6 -1.5 31.4 4th 24.5 -0.9 22.4 28th 0 42.1 v low 0%
Truscott 29.9   32.2 3rd 19.0   13.4 28th 0
Wyndham 30.9 -2.7 34.1 3rd 16.8 -3.9 11.0 29th 0 8.6 lowest 0%
Wyndham Aero 31.5 -2.6 35.1 3rd 16.5 -2.8 10.1 29th 0 11.4 v low 0%
East Kimberley (district 02)
Argyle Aerodrome 29.2 -2.7 32.9 3rd 16.0 -3.1 10.1 27th        
Halls Creek Airport 27.4 -2.5 31.4 2nd 14.7 -2.1 9.6 28th 0 12.9 lowest 0%
Kununurra Aero 30.0 -2.9 33.5 3rd 15.4 -3.6 10.4 29th 0 7.3 lowest 0%
Warmun 29.5 -2.8 33.4 2nd 13.9 -3.4 7.0 28th 0 10.5 lowest 0%
West Kimberley (district 03)
Bidyadanga 31.3 -1.1 34.8 1st 17.3 -1.1 11.8 31st 5.3 25.2 average 21%
Broome Airport 30.5 -1.1 33.8 1st 17.5 -0.8 10.8 28th 0.4 26.4 average 2%
Curtin Aero 31.4 -1.9 34.9 4th 18.2 -1.0 13.1 19th 1.0 12.9 average 8%
Derby Aero 31.2 -1.6 34.1 4th 17.1 -1.9 9.1 30th 1.2 18.1 average 7%
Fitzroy Crossing Aero 30.9 -2.4 34.4 4th 15.1 -0.8 8.8 28th 0 7.9 v low 0%
West Roebuck 31.6 -1.5 35.0 20th 16.5 +0.5 10.4 27th 0.2 10.9 average 2%
De Grey (district 04)
Bedout Island 26.7   30.0 21st 21.9   19.0 7th
Karratha Aero 27.0 -3.2 31.4 1st 17.5 -0.7 11.3 26th 132.4 25.1 v high 527%
Legendre Island 26.1   29.9 21st 20.4   16.8 16th
Marble Bar 27.6 -3.9 32.3 19th 16.0 -1.2 9.4 30th 22.0 9.2 high 239%
Port Hedland Airport 28.5 -2.1 32.5 21st 17.0 -0.2 11.5 29th 36.8 27.4 high 134%
Roebourne 28.0 -2.5 32.8 21st 16.8 -1.5 11.5 31st 61.3 27.8 high 221%
Roebourne Aero 27.8   32.5 1st 17.0   10.0 30th 72.4 17.2 v high 421%
Fortescue (district 05)
Barrow Island Airport 25.3 -2.3 28.7 1st 20.3 -1.0 16.6 27th 94.2 61.1 high 154%
Learmonth Airport 27.7 -0.8 31.3 1st 16.8 +0.6 11.7 26th 21.6 40.9 average 53%
Mardie 28.7 -2.8 32.6 1st 16.6 -0.3 11.5 29th 57.0 36.9 high 154%
Onslow 28.6 -0.3 32.0 18th 18.5 +2.2 13.8 28th 15.8 45.9 average 34%
Onslow Airport 28.4 -0.8 32.2 19th 18.0 +0.8 13.7 26th 16.8 51.9 average 32%
Wittenoom 25.0 -2.7 29.2 21st 14.9 -1.2 10.4 31st 41.3 27.7 high 149%
West Gascoyne (district 06)
Carnarvon Airport 26.8 +0.6 31.4 8th 14.4 -0.5 9.7 28th 21.2 35.7 average 59%
Denham 25.7 -0.1 31.6 8th 16.7 +0.3 12.5 23rd 19.4 37.9 average 51%
Emu Creek Station 29.1 -0.8 32.6 19th 17.1 +1.1 11.5 27th 10.8 35.6 average 30%
Gascoyne Junction 26.7 -1.0 30.7 8th 14.8 +1.0 10.9 23rd 52.4 27.6 high 190%
Murchison 25.1 -0.9 30.2 7th 11.0 -0.4 6.4 27th 34.9 19.3 high 181%
Shark Bay Airport 26.8 -0.7 31.8 8th 14.4 -0.4 9.8 29th 24.8 25.7 average 96%
East Gascoyne (district 07)
Newman Aero 24.0 -3.3 28.9 20th 12.2 +0.6 6.2 30th        
Paraburdoo Aero 26.5 -2.8 30.9 20th 15.3 +0.7 10.1 30th 3.2 16.9 average 19%
Murchison (district 07A)
Meekatharra Airport 22.8 -1.0 27.5 20th 11.6 -0.5 7.0 22nd 2.2 22.9 low 10%
Mount Magnet Aero 22.5 -1.5 26.9 29th 11.0 -0.8 5.1 22nd 14.4 17.8 average 81%
North Coast (district 08)
Carnamah 23.5 +0.9 30.4 8th 11.9 +1.1 6.3 22nd 75.9 51.4 high 148%
Dalwallinu 22.0 -0.3 27.9 8th 10.0 -0.2 5.5 22nd 45.0 38.1 average 118%
Dalwallinu Comparison 22.5 +0.7 28.8 8th 10.8 +0.6 6.3 22nd 46.2 45.8 average 101%
Geraldton Airport 25.3 +1.3 31.7 8th 13.0 +0.1 6.8 22nd 87.4 70.0 high 125%
Kalbarri 27.1 +1.2 32.7 7th 13.7 +0.5 8.4 27th 83.5 58.5 high 143%
Morawa Airport 23.8 -0.4 29.0 8th 10.3 -0.4 5.0 22nd 62.6 39.8 high 157%
Mullewa 24.4 +0.7 30.0 8th 12.5 +1.4 7.0 22nd 68.4 47.2 high 145%
North Island 25.1 +0.7 28.8 8th 19.0 +0.4 13.9 19th 69.8 47.7 high 146%
Wongan Hills 22.4 +0.9 28.6 8th 10.6 +0.7 5.0 22nd 73.4 53.0 high 138%
Central Coast (district 09)
Badgingarra Research Stn 22.8 +0.3 29.9 8th 11.5 +0.9 5.5 22nd 76.4 70.8 average 108%
Bickley 20.5 +1.1 26.6 8th 10.4 +0.2 6.0 21st 104.0 130.2 average 80%
Champion Lakes 22.7   28.4 8th 12.9   6.0 21st 67.0
Garden Island HSF 22.6   28.4 8th 14.3   11.0 21st 79.0 73.2 high 108%
Gingin Aero 23.3 +0.4 30.4 8th 10.0 +0.7 3.1 22nd        
Gooseberry Hill 22.0 +0.8 28.2 8th 12.4 +0.2 7.6 21st
Gosnells City 23.9 +1.1 30.6 8th     5.0 21st 60.6 104.5 low 58%
Jandakot Aero 23.5 +1.5 29.5 8th 9.7 +0.3 1.6 21st 85.6 107.7 average 79%
Jurien Bay 24.8 +1.6 28.6 8th 11.7 -0.1 6.5 22nd 90.3 78.7 high 115%
Karnet                 94.0 140.1 average 67%
Lancelin 24.7 +2.1 31.0 8th 12.3 -0.2 7.0 22nd 43.5 84.4 low 52%
Medina Research Centre 23.7 +1.7 30.5 8th 11.1 +0.6 4.0 21st 85.0 97.7 average 87%
Pearce RAAF 23.4 +1.5 29.8 8th 11.3 +0.5 3.4 21st 41.8 85.5 low 49%
Perth Airport 23.6 +1.9 29.9 8th 11.0 +0.6 3.1 21st 56.6 100.1 low 57%
Perth Metro* 23.2 +0.8 30.0 8th 11.0 +0.5 4.5 21st 85.0 117.4 average 72%
Rottnest Island 21.9 +0.8 27.4 8th 15.7 +0.4 11.8 21st 86.2 106.2 average 81%
Swanbourne 23.5 +1.3 29.6 8th 12.6 0.0 7.3 21st 94.6 89.5 average 106%
South Coast (district 09A)
Albany 19.9 +1.3 25.0 29th 12.6 +1.9 8.4 28th 86.5 117.4 average 74%
Albany Airport 19.5 +0.6 24.4 8th 10.2 +0.4 4.3 28th 82.6 91.4 average 90%
Bridgetown 19.9 +0.1 25.1 8th 6.7 -0.2 0.9 28th 61.6 99.5 low 62%
Bridgetown Comparison 21.1 +1.9 25.9 8th 6.2 -0.3 0.9 29th 55.0 109.5 low 50%
Bunbury 21.7 +0.6 25.1 8th 9.6 +0.2 3.6 28th 64.8 91.6 average 71%
Busselton 21.2 +0.7 24.2 4th 10.0 -0.4 5.2 27th 49.6 93.8 low 53%
Busselton Aero 21.1 +0.4 23.5 8th 8.9 -0.4 4.4 29th 58.0 100.6 low 58%
Cape Leeuwin 20.4 +1.3 24.4 8th 14.1 +0.4 10.6 27th 81.0 138.1 low 59%
Cape Naturaliste 20.8 +1.6 24.5 4th 12.9 +0.3 9.7 21st 54.6 115.4 v low 47%
Collie East 20.6   25.8 8th 6.2   1.2 28th 63.4
Donnybrook 21.6 +1.6 27.5 8th 9.3 +1.1 5.0 21st 119.2 134.3 average 89%
Dwellingup 20.7 +2.3 26.6 8th 8.4 +0.7 3.8 28th 83.4 156.9 low 53%
Esperance 20.7 +0.2 26.6 16th 12.0 +1.0 6.9 8th 48.8 71.1 average 69%
Esperance Aero 20.2 0.0 25.5 16th 11.0 +0.4 6.4 8th 62.6 67.2 average 93%
Harvey 22.0 +0.5 27.5 8th 9.8 -0.8 4.0 21st 82.4 108.1 average 76%
Hopetoun North 20.8 -0.7 26.7 29th 11.8 +1.3 5.5 8th 108.0 45.1 v high 239%
Jarrahwood 20.9 +1.0 25.7 8th 6.0 -0.9 1.0 28th 75.8 125.0 low 61%
Mandurah 22.2   25.0 7th 13.8   9.5 21st 82.0 94.6 average 87%
Manjimup 19.5 +1.9 24.3 4th 9.1 +0.2 4.8 27th 63.2 131.0 v low 48%
North Walpole 19.6   24.6 4th 11.5   6.6 27th
Pemberton 19.7 +1.6 24.7 4th 9.8 +0.4 5.5 29th 83.2 150.2 low 55%
Rocky Gully 18.9 +0.2 24.0 4th 9.2 -0.2 4.1 12th 66.4 73.4 average 90%
Shannon 18.6 +0.1 23.2 4th 8.8 -0.4 4.1 28th 95.2 125.7 average 76%
Windy Harbour 20.1 +0.2 24.3 4th 9.8 -0.9 3.9 27th 129.6 140.0 average 93%
Witchcliffe 19.9 0.0 24.2 4th 8.9 -1.0 4.5 27th 123.2 129.7 average 95%
North Central (district 10)
Bencubbin 21.3 +0.5 26.6 9th 10.1 +1.0 5.9 1st 46.8 37.3 high 125%
Cunderdin Airfield 22.3 +0.4 28.4 8th 9.4 +1.0 4.3 1st 38.2 31.8 average 120%
Kellerberrin 22.0 +1.2 28.0 9th 7.8 -0.5 2.1 12th 23.9 42.1 average 57%
Merredin 21.7 +1.1 27.5 9th     3.5 22nd 36.4 41.2 average 88%
Northam 22.8 +1.6 28.8 8th 9.1 +0.7 4.2 23rd 50.0 55.5 average 90%
York 22.4 +0.5 28.6 8th 8.2 +1.2 3.5 28th 38.3 43.8 average 87%
South Central (district 10A)
Beverley 22.6 +1.2 28.8 8th 8.8 +0.9 4.0 21st 51.2 53.9 average 95%
Brookton 21.2 +0.7 27.2 8th 9.5 +1.8 5.1 28th 38.7 57.2 average 68%
Corrigin 20.5 +0.9 25.8 29th 9.0 +1.5 4.8 12th 28.8 47.5 low 61%
Hyden 21.7 +0.9 27.3 9th 9.4 +1.8 4.5 23rd 22.6 39.3 low 58%
Katanning 19.6 +0.1 25.2 8th 9.1 +0.3 5.2 27th 46.8 45.4 average 103%
Katanning Comparison 20.1 +1.6 25.5 5th 7.9 0.0 2.4 27th 39.4 59.8 low 66%
Lake Grace 20.0 -0.3 25.7 29th 9.7 +0.9 5.8 7th 31.8 27.2 average 117%
Lake Grace Comparison 20.2 +0.5 25.7 29th 9.8 +1.2 6.4 7th 32.2 43.1 average 75%
Narembeen 21.8 +0.9 27.0 9th 9.5 +1.3 5.0 1st 40.1 39.8 average 101%
Narrogin 20.0 +1.5 25.0 8th 8.7 +0.9 3.6 27th 33.4 62.9 low 53%
Newdegate Research Station 20.0 -0.1 25.6 29th 7.4 +0.1 2.4 12th 23.0 43.4 low 53%
Ongerup 19.7 +0.8 25.1 29th 9.2 +0.6 5.0 12th 34.4 43.9 average 78%
Pingelly 20.8 +1.2 26.3 8th 10.0 +1.2 5.7 21st 41.8 57.8 average 72%
Ravensthorpe         9.8 +0.2 4.5 27th 36.6 44.1 average 83%
Wagin 20.4 +0.9 25.4 8th 8.0 0.0 3.0 27th 37.9 54.3 average 70%
Wandering 20.9 +0.7 26.5 8th 7.0 +0.7 2.1 28th 49.4 48.6 average 102%
Eucla (district 11)
Balladonia 20.5 -0.4 26.0 16th 8.6 +0.6 2.9 28th 14.8 26.4 average 56%
Eucla 19.9 -1.2 26.1 31st 10.7 +0.2 4.3 29th 41.4 31.0 high 134%
Eyre 20.8 -0.5 26.4 6th 8.7 -0.5 -2.4 28th 54.4 38.7 high 141%
Forrest 19.4 -3.0 24.0 31st 8.8 0.0 1.4 28th 11.2 17.7 average 63%
Red Rocks Point 20.1   25.3 6th 12.1   5.5 28th 54.2
South East (district 12)
Bulga Downs 23.2   27.0 28th 9.2   4.8 25th 40.8 26.0 high 157%
Kalgoorlie-Boulder Airport 19.9 -0.8 25.0 16th 9.4 +0.7 5.8 12th 30.2 26.3 average 115%
Laverton Aero 20.8 -1.3 24.8 20th 9.8 -0.8 3.3 22nd 12.6 13.8 average 91%
Leinster Aero 21.5 -1.7 26.9 20th 9.6 -1.1 4.5 23rd 1.4 15.9 low 9%
Leonora 21.4 -1.4 25.9 17th 9.8 -0.4 6.0 23rd 12.8 24.1 average 53%
Leonora Aero 21.5   25.8 20th 10.3   5.8 22nd 12.4
Munglinup West 20.6   25.1 16th 10.0   6.5 12th 73.6 42.3 high 174%
Norseman 20.1 -0.3 25.0 16th 8.9 +0.4 3.0 12th 42.9 30.7 high 140%
Norseman Aero 19.8 -1.4 25.2 16th 7.8 +0.7 1.3 12th 42.6 19.7 high 216%
Salmon Gums Res.Stn. 20.3 +0.5 26.6 16th 7.2 0.0 -0.9 8th 30.8 34.3 average 90%
Southern Cross Airfield 20.7 -0.8 25.7 29th 8.2 +0.7 3.1 27th 18.2 31.3 average 58%
Yeelirrie 22.0 -1.5 27.5 20th 7.9 -0.4 1.7 22nd 3.3 24.8 low 13%
North East (district 13)
Carnegie 22.6 -2.8 27.3 20th 10.0 -0.8 5.4 28th 7.6 15.8 average 48%
Giles Meteorological Office 21.9 -1.8 28.1 21st 9.2 -2.2 4.9 24th 3.2 19.5 average 16%
Telfer Aero 25.9 -3.2 30.7 21st 14.0 -1.3 7.5 29th 9.4 19.0 average 49%
Warburton Airfield 22.3 -2.0 26.9 20th 9.2 -1.2 1.6 29th        
Wiluna 22.7 -1.1 28.3 21st 10.2 +0.2 5.4 22nd 4.3 25.3 low 17%
Offshore Islands (district 200)
Christmas Island Aero 27.4 -0.4 28.5 25th 23.4 -0.4 21.0 7th 172.2 176.7 average 97%
Cocos Island Airport 29.1 -0.1 29.8 30th 25.3 +0.3 23.4 1st 164.0 193.3 average 85%
Varanus Island 25.7 -2.4 28.8 1st 22.0 -1.7 17.8 13th 47.4 32.5 average 146%

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 11 am on Wednesday 1 June 2011. 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.

Records in this summary are based on sites with at least 30 years of data.

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

Further information

Media
(03) 9669 4057
Enquiries