Greater Perth in summer 2018-19: a dry summer

Rainfall in summer 2018-19 was well below average across the Greater Perth. Daytime and overnight temperatures were generally below average.

Below average rainfall

  • Summer rainfall totals were mostly less than 10 mm, up to 15-20 mm in the Perth hills
  • Perth Metro recorded 9.2 mm, which was the driest summer since 2013-14 (2.0 mm)
  • Garden Island recorded 2.2 mm, which was the lowest summer total in Greater Perth, and its driest summer since 2009-10 (1.2 mm)

Below average daytime and overnight temperatures

  • Mean maximum temperatures were generally below average, except Perth Airport and Pearce RAAF having above average mean maximum temperature
  • Swanbourne's mean maximum temperature ( 27.6 °C) was the second-coolest summer on record, behind 26.8 °C in summer 2005-06
  • Perth Metro's mean maximum temperature ( 30.5 °C) was 0.2 °C below average, though it was warmer than summers in 2017-18 and 2016-17
  • The summer's hottest day was on 20 January 2019, with daily maxima in the low to mid-40s for most sites away from the coast; 44.4 °C at Pearce RAAF was the highest temperature of the season
  • Mean minimum temperatures were below average across Greater Perth
  • Pearce RAAF's mean minimum temperature (15.3 °C) was coolest summer since 2005-06 when 15.2 °C was recorded
  • Perth Metro's mean minimum temperature (16.9 °C) was 0.7 °C below average, which was cooler than summer 2017-18

Perth Metro

  • Total rainfall for Perth Metro was 9.2 mm, which is 22% of the long-term average of 42.7 mm
  • The warmest day was 42.1 °C on 20 January, and the coolest day was on 24 January when the temperature reached 20.6 °C
  • The coldest morning was 10.0 °C on 4 January, and the warmest morning was on 22 December when the minimum temperature was 23.5 °C

Further information

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Extremes in summer 2018-19
Hottest day 44.4 °C at Pearce RAAF on 20 Jan 2019
Warmest days on average 33.1 °C at Pearce RAAF
Coolest days on average 25.0 °C at Rottnest Island
Coldest day 17.3 °C at Bickley on 24 Jan 2019
Coldest night 6.8 °C at Pearce RAAF on 7 Dec 2018
6.8 °C at Jandakot Aero on 4 Jan 2019
Coolest nights on average 14.8 °C at Bickley
Warmest nights on average 18.2 °C at Rottnest Island
Warmest night 25.9 °C at Pearce RAAF on 22 Dec 2018
Warmest on average overall 24.2 °C at Pearce RAAF
Coolest on average overall 21.6 °C at Rottnest Island
Wettest overall 33.2 mm at Karnet
Driest overall 2.2 mm at Garden Island HSF
Wettest day 20.1 mm at Karnet on 24 Jan 2019
Strongest wind gust 85 km/h at Jandakot Aero on 14 Dec 2018

Summary statistics for summer 2018-19
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2018-19
Diff
from
average
Highest for
summer
2018-19
Mean for
summer
2018-19
Diff
from
average
Lowest for
summer
2018-19
Total for
summer
2018-19
Average
for
summer
Rank of
summer
2018-19
Fraction of
summer
average
Bickley 29.6 -0.1 40.4 20 Jan 2019 14.8 -0.2 8.4 4 Jan 2019 18.4 55.5 low 33%
Garden Island HSF 25.4 -1.6 38.7 22 Dec 2018 18.0 -0.5 13.5 6 Dec 2018 2.2 41.6 v low 5%
Jandakot Aero 30.2 -0.5 42.0 20 Jan 2019 15.6 -0.6 6.8 4 Jan 2019 7.6 46.1 low 16%
Mandurah 28.0 -0.7 35.8 21 Dec 2018 17.8 -0.7 13.2 25 Jan 2019 9.6 47.3 low 20%
Millendon (Swan Valley) 32.1   43.9 20 Jan 2019 15.5   8.0 7 Dec 2018 12.6
Pearce RAAF 33.1 +0.7 44.4 20 Jan 2019 15.3 -1.1 6.8 7 Dec 2018 6.4 32.5 low 20%
Perth Airport 31.3 +0.4 42.9 20 Jan 2019 16.1 -0.4 7.0 4 Jan 2019 6.8 37.2 low 18%
Perth Metro 30.5 -0.2 42.1 20 Jan 2019 16.9 -0.7 10.0 4 Jan 2019 9.2 42.7 low 22%
Rottnest Island 25.0 -1.3 37.9 22 Dec 2018 18.2 -0.5 13.6 6 Dec 2018 11.6 39.3 average 30%
Swanbourne 27.6 -1.8 39.0 22 Dec 2018 17.4 -0.4 11.3 25 Jan 2019 6.8 42.2 low 16%

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 9 am on Friday 1 March 2019. 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
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