Greater Perth in winter 2018: Above average rainfall

Rainfall in winter 2018 was above average cross Perth, and being the wettest winter for fifteen years at Perth Metro since records commenced in 1993, though it had been the wettest winter for over two decades at Perth Airport and other sites. Mean maximum temperatures were close to average for most sites, while mean minimum temperatures were slightly above average.

Above average rainfall

  • Rainfall in winter 2018 was above average across Perth; monthly rainfall totals were in the 300 mm-500 mm range for most sites, reaching 700 mm-800 mm in the Perth hills
  • Perth Metro had its wettest winter since 2003 when an equal total of 464.4 mm was recorded
  • Perth Airport, Bickley, Pearce RAAF, Swanbourne had their wettest winter for 22 years while Jarrahdale in the southeast had its wettest winter for 35 years

Above average overnight temperatures

  • Winter mean maximum temperatures varied from 0.2 °C or 0.3 °C below average near the coast and in the hills, to 0.5 °C above average at Perth Airport and Pearce RAAF
  • Winter mean minimum temperatures are slightly above average for most sites
  • Winter extreme temperatures in the Perth area all occurred in August ranging from the lowest 1.0 °C at Karnet on the 11th to the highest 25.8 °C at Jandakot Aero on the 20th

Perth Metro

  • Total rainfall for Perth Metro was 464.4 mm, which was the wettest winter for 15 years
  • The mean maximum temperature for Perth Metro was 18.9 °C, which was 0.1 °C below average
  • The warmest day was 25.3 °C on 20 August, and the coolest day was 14.1 °C on 7 June
  • The mean minimum temperature for Perth Metro was 8.7 °C, which was 0.5 °C above average
  • The coldest morning was 2.8 °C on 11 August, and the warmest morning was 15.0 °C on 20 August

Further information

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Extremes in winter 2018
Hottest day 25.8 °C at Jandakot Aero on 20 Aug
Warmest days on average 19.0 °C at Perth Airport
Coolest days on average 15.5 °C at Bickley
Coldest day 10.1 °C at Bickley on 29 Aug
Coldest night 1.0 °C at Karnet on 11 Aug
Coolest nights on average 7.7 °C at Bickley
Warmest nights on average 12.9 °C at Rottnest Island
11.1 °C at Mandurah
Warmest night 17.4 °C at Rottnest Island on 2 Jul
Warmest on average overall 15.6 °C at Rottnest Island
Coolest on average overall 11.6 °C at Bickley
Wettest overall 781.2 mm at Bickley
Driest overall 320.4 mm at Rottnest Island
Wettest day 81.0 mm at Jarrahdale on 10 Jun
Strongest wind gust 109 km/h at Rottnest Island on 5 Jun

Highest winter total rainfall for at least 20 years
Observed
(mm)
Most recent
higher
Average for
winter
Jarrahdale 752.6 799.0 in 1983* 634.6
Bickley 781.2 877.7 in 1996 589.4
Perth Airport 482.0 567.4 in 1996 430.5
Swanbourne 486.4 496.0 in 1996 393.2
Pearce RAAF 461.8 510.0 in 1996* 369.8

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




Summary statistics for winter 2018
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
winter
2018
Diff
from
average
Highest for
winter
2018
Mean for
winter
2018
Diff
from
average
Lowest for
winter
2018
Total for
winter
2018
Average
for
winter
Rank of
winter
2018
Fraction of
winter
average
Bickley 15.5 -0.2 22.2 20 Aug 7.7 +0.1 2.8 10 Aug 781.2 589.4 high 133%
Garden Island HSF 18.1 -0.2 23.3 20 Aug 11.6 +0.1 5.6 19 Aug 389.8 318.1 high 123%
Jandakot Aero 18.6 0.0 25.8 20 Aug 8.0 +0.8 1.4 12 Aug 516.4 455.0 high 113%
Mandurah 17.8 -0.3 21.8 10 Jul 11.1 0.0 5.7 10 Aug 403.8 336.3 v high 120%
Millendon (Swan Valley) 18.8   24.3 19 Aug 8.3   2.4 11 Aug 411.0
Pearce RAAF 18.9 +0.5 24.3 20 Aug 8.9 +0.3 2.6 11 Aug 461.8 369.8 high 125%
Perth Airport 19.0 +0.5 25.3 20 Aug 8.7 +0.4 2.5 10 Aug 482.0 430.5 high 112%
Perth Metro 18.9 -0.1 25.3 20 Aug 8.7 +0.5 2.8 11 Aug 464.4 396.4 high 117%
Rottnest Island 18.3 +0.2 22.3 20 Aug 12.9 +0.2 6.8 10 Aug 320.4 303.0 average 106%
Swanbourne 18.7 -0.2 25.7 20 Aug 10.5 +0.4 5.2 11 Aug 486.4 393.2 high 124%

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.

This summary includes 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 8 am on Monday 3 September 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

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