Greater Perth in summer 2019-20: a warm summer

Summer 2019–2020 was very warm, with below average summer rainfall for most sites in Greater Perth. Mean maximum and minimum temperatures were more than one degree above average for most sites.

Summer rainfall below average for most sites

  • Summer rainfall totals varied from 10–30 mm for most coastal sites and offshore islands, up to 40–70 mm in the Perth hills and at Perth Metro
  • Perth Metro recorded 39.8 mm in total this summer, with 12 rain days (3 days each in December and January, 6 days in February); the rainfall total was slightly below its summer average(42.6 mm), but wetter than summer 2018-19

Temperatures above average

  • Mean maximum and minimum temperatures were 1–2 °C above average for most sites
  • Bickley, Jandakot Aero and Swanbourne equalled their warmest summer on record in terms of minimum temperatures
  • Perth Metro's summer mean maximum and minimum temperature was 32.0 °C and 18.6 °C, its equal second-highest and fourth-highest for summer on record respectively
  • Perth Metro reported six days (four in December, two in February) with maximum temperatures at 40 °C or higher, including 42.7 °C on 4 February, which was its hottest summer day since 5 January 2015 (44.4 °C)
  • Very warm nights with minimum temperature in the mid–20s were reported on 6 December, 5 and 20 February for many coastal plain sites

Perth Metro

  • Total rainfall for Perth Metro was 39.8 mm, which is 93% of the long-term average of 42.6 mm
  • The warmest day was 42.7 °C on 4 Feb, and the coolest day was on 3 Jan when the temperature reached 22.1 °C
  • The coldest morning was 12.7 °C on 4 Jan, and the warmest morning was on 20 Feb when the minimum temperature was 24.6 °C

Further information

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Extremes in summer 2019-20
Hottest day 44.6 °C at Pearce RAAF on 4 Feb 2020
Warmest days on average 34.2 °C at Pearce RAAF
Coolest days on average 27.3 °C at Rottnest Island
Coldest day 19.9 °C at Garden Island HSF on 3 Jan 2020
Coldest night 8.2 °C at Bickley on 4 Jan 2020
Coolest nights on average 16.2 °C at Bickley
Warmest nights on average 19.7 °C at Garden Island HSF
19.7 °C at Mandurah
19.7 °C at Rottnest Island
Warmest night 27.1 °C at Pearce RAAF on 6 Dec 2019
Warmest on average overall 25.9 °C at Pearce RAAF
Coolest on average overall 23.5 °C at Bickley
23.5 °C at Rottnest Island
Wettest overall 68.6 mm at Bickley
Driest overall 10.0 mm at Mandurah
Wettest day 22.8 mm at Bickley on 27 Feb 2020
Strongest wind gust 93 km/h at Ocean Reef on 25 Feb 2020

Record highest summer mean daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
summer
Jandakot Aero 18.0 = 18.0 in 2011 29 16.2
Swanbourne 19.3 = 19.3 in 2011 26 17.8
Bickley 16.2 = 16.2 in 2010 25 15.0



Summary statistics for summer 2019-20
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2019-20
Diff
from
average
Highest for
summer
2019-20
Mean for
summer
2019-20
Diff
from
average
Lowest for
summer
2019-20
Total for
summer
2019-20
Average
for
summer
Rank of
summer
2019-20
Fraction of
summer
average
Bickley 30.7 +1.0 39.6 15 Dec 2019 16.2 +1.2 8.2 4 Jan 2020 68.6 55.7 high 123%
Garden Island HSF 27.9 +0.9 40.3 4 Feb 2020 19.7 +1.2 12.9 4 Jan 2020 17.4 40.3 average 43%
Jandakot Aero 31.9 +1.2 41.6 4 Feb 2020 18.0 +1.8 9.4 31 Jan 2020 14.6 45.4 low 32%
Karnet 30.7 +1.0 39.2 27 Jan 2020     8.3 5 Jan 2020 29.6 57.9 average 51%
Mandurah 29.7 +1.0 40.1 4 Feb 2020 19.7 +1.3 12.0 4 Jan 2020 10.0 45.3 average 22%
Millendon (Swan Valley) 33.4   43.6 4 Feb 2020 17.5   9.4 31 Jan 2020 32.2
Pearce RAAF 34.2 +1.8 44.6 4 Feb 2020 17.6 +1.2 10.1 31 Jan 2020 17.6 32.3 average 54%
Perth Airport 32.8 +1.9 43.3 4 Feb 2020 18.1 +1.6 9.2 31 Jan 2020 22.6 37.0 average 61%
Perth Metro 32.0 +1.3 42.7 4 Feb 2020 18.6 +1.0 12.7 4 Jan 2020 39.8 42.6 average 93%
Rottnest Island 27.3 +1.1 38.6 4 Feb 2020 19.7 +1.0 13.4 4 Jan 2020 11.0 38.2 average 29%
Swanbourne 29.6 +0.3 42.1 4 Feb 2020 19.3 +1.5 12.7 4 Jan 2020 25.6 41.6 average 62%

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 Tuesday 3 March 2020. 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