Greater Perth in summer 2017-18: A wet summer with mild temperatures

Rainfall in summer 2017-18 was above average across the Greater Perth region, mostly due to a very wet January. Mean maximum temperatures were generally below average, whilst mean minimum temperatures were mostly near average.

Above average rainfall across Greater Perth

  • Summer rainfall totals were above average and generally ranged from 100 mm to 180 mm for most coastal plain sites and offshore Islands, reaching 200 mm to 240 mm in the hills
  • A cloudband associated with ex-tropical cyclone Joyce brought persistent rain to Perth in mid-January; daily rainfall totals between 50 mm and 150 mm were registered on the 16th, and a summer daily rainfall record for many sites
  • A hand-full of sites in the Perth hills, as well as Rottnest Island, had their wettest summer on record, whilst a few sites had their highest total summer rainfall for at least 20 years

Below average mean maximum temperature; near average mean minimum temperature

  • Mean maximum temperatures were 0.5 °C to 1.5 °C below average for most sites
  • Mean minimum temperatures were mostly near average, but were above average at Perth Airport and Jandakot Aerodrome
  • Temperatures failed to reach 40 °C in December and February, whilst only three daily maximum temperatures of 40 °C or greater were recorded in January: 40.0 °C at Pearce RAAF on the 1st, and 40.3 °C at Mandurah and 40.1 °C at Garden Island on the 14th

Perth Metro

  • Total summer rainfall for Perth Metro was 147.0 mm, which is over three times of average and the 2nd-highest summer rainfall at Perth Metro; it also ranked fourth-highest summer rainfall for Perth city from records going back to 1876
  • Daily rainfall of 96.2 mm on 16 January at Perth Metro was the fourth-highest daily rainfall total in summer for the city, only behind 120.6 mm on 6 February 1992, 114.4 mm on 10 February 2017, and 104.0 mm on 22 January 2000
  • The mean maximum temperature for Perth Metro was 30.1 °C,which is 0.6 °C below average, but higher than last summer when a mean of 29.8 °C was recorded
  • Perth Metro recorded 10 hot days with daily maximum temperatures 35 °C or higher, which is the least number of hot days for 17 summer seasons, since 2000-01 when 9 hot days were recorded
  • Perth Metro failed to record a day at or above 40 °C throughout summer, the first time this has occurred for 16 summers, since 2001-02
  • The mean minimum temperature for Perth Metro was 17.6 °C, which is near average

Further information

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Extremes in summer 2017-18
Hottest day 40.3 °C at Mandurah on 14 Jan 2018
Warmest days on average 32.3 °C at Pearce RAAF
Coolest days on average 25.3 °C at Rottnest Island
Coldest day 16.7 °C at Bickley on 18 Dec 2017
Coldest night 8.0 °C at Karnet on 12 Jan 2018
Coolest nights on average 14.9 °C at Bickley
Warmest nights on average 18.5 °C at Rottnest Island
Warmest night 24.7 °C at Pearce RAAF on 3 Feb 2018
24.7 °C at Perth Metro on 3 Feb 2018
Warmest on average overall 24.4 °C at Pearce RAAF
Coolest on average overall 21.8 °C at Bickley
Wettest overall 239.2 mm at Huntly
Driest overall 94.8 mm at Millendon (Swan Valley)
Wettest day 147.6 mm at Karragullen on 16 Jan 2018
Strongest wind gust 130 km/h at Garden Island HSF on 25 Feb 2018

Record highest summer daily rainfall
New record
(mm)
Old
record
Years of
record
Jarrahdale 125.2 on 16 Jan 2018 109.0 on 9 Feb 1992 122
Wanneroo 94.6 on 16 Jan 2018 78.8 on 10 Feb 2017 81
Wooroloo 90.4 on 16 Jan 2018 79.2 on 10 Feb 2017 77
Pearce RAAF 66.8 on 16 Jan 2018 58.0 on 10 Feb 2017 67
Gidgegannup 114.2 on 16 Jan 2018 113.5 on 29 Jan 1990 61
Karnet 131.3 on 16 Jan 2018 115.8 on 10 Feb 2017 56
Roleystone 139.2 on 16 Jan 2018 135.4 on 9 Feb 1992 52
Karragullen North 138.6 on 16 Jan 2018 102.4 on 22 Feb 1986 51
Bickley 139.2 on 16 Jan 2018 83.6 on 10 Feb 2017 50
Karragullen 147.6 on 16 Jan 2018 95.0 on 22 Jan 2000 47
Pickering Brook 131.4 on 16 Jan 2018 100.6 on 22 Feb 1986 43
Fremantle 128.4 on 16 Jan 2018 76.8 on 10 Feb 2017 31
Pickering Brook North 134.6 on 16 Jan 2018 92.0 on 29 Jan 1990 31
Huntly 144.0 on 16 Jan 2018 128.0 on 10 Feb 2017 29
Rottnest Island 142.2 on 16 Jan 2018 93.8 on 10 Feb 2017 26
Swanbourne 138.6 on 16 Jan 2018 97.4 on 10 Feb 2017 26



Record highest summer total rainfall
New record
(mm)
Old
record
Years of
record
Average for
summer
Jarrahdale 221.2 185.3 in 1954 130 49.6
Roleystone 190.4 178.6 in 1991 50 51.9
Bickley 208.4 171.8 in 2016 47 56.2
Karragullen North 212.6 184.4 in 1999 38 50.8
Pinjarra Refinery 99.0 97.5 in 2016 29 42.7
Huntly 239.2 198.7 in 2016 27 60.6
Rottnest Island 183.4 117.6 in 2016 23 40.5

Highest summer total rainfall for at least 20 years
Observed
(mm)
Most recent
higher
Average for
summer
Serpentine 169.4 204.4 in 1954* 37.5
Jandakot Aero 149.2 244.0 in 1991* 47.0

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




Summary statistics for summer 2017-18
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2017-18
Diff
from
average
Highest for
summer
2017-18
Mean for
summer
2017-18
Diff
from
average
Lowest for
summer
2017-18
Total for
summer
2017-18
Average
for
summer
Rank of
summer
2017-18
Fraction of
summer
average
Bickley 28.8 -1.0 36.4 2 Jan 2018 14.9 -0.1 8.9 6 Jan 2018 208.4 56.2 highest 371%
Garden Island HSF 26.0 -1.1 40.1 14 Jan 2018 18.4 -0.1 13.6 1 Dec 2017 141.8 43.9 high 323%
Jandakot Aero 30.2 -0.5 38.6 15 Feb 2018 16.7 +0.5 8.1 6 Jan 2018 149.2 47.0 v high 317%
Mandurah 28.1 -0.7 40.3 14 Jan 2018 18.2 -0.3 13.3 1 Dec 2017 124.4 49.5 high 251%
Millendon (Swan Valley) 31.7   39.8 2 Jan 2018 16.6   9.9 12 Jan 2018 94.8
Pearce RAAF 32.3 -0.1 40.0 2 Jan 2018 16.6 +0.2 9.7 12 Jan 2018 107.2 33.0 v high 325%
Perth Airport 31.0 +0.1 39.0 15 Feb 2018 17.1 +0.6 9.1 12 Jan 2018 112.4 37.5 v high 300%
Perth Metro 30.1 -0.6 38.0 14 Jan 2018 17.6 0.0 12.4 18 Dec 2017 147.0 44.1 v high 333%
Rottnest Island 25.3 -1.0 35.9 14 Jan 2018 18.5 -0.2 11.4 18 Dec 2017 183.4 40.5 highest 453%
Swanbourne 27.9 -1.6 38.7 14 Jan 2018 18.0 +0.2 12.4 6 Jan 2018 160.2 43.7 v high 367%

Notes

The Seasonal climate summary, generally published on the first working day of each month, lists the main features of the weather in Greater Perth 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.

In September 2017 this summary was broadened to include data from observing sites in or near the Greater Perth “Greater Capital City Statistical Area” (GCCSA). The Australian Bureau of Statistics designed the GCCSAs to “include the population within the urban area of the city, as well as people who regularly socialise, shop or work within the city, and live in small towns and rural areas surrounding the city. It is important to note that GCCSAs do not define the built up edge of the city. They provide a stable definition for these cities and are designed for the output of a range of social and economic survey data.

This statement has been prepared based on information available at 9 am on Thursday 1 March 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