Greater Perth in summer 2020-21: a very warm and dry start, with mild and wet finish

Summer rainfall was above average at most sites across Greater Perth. During summer, Perth experienced a very warm December and January, including a spell of 40 °C degree days to leading to Christmas Day, though February was generally mild.

Above average rainfall

  • Summer rainfall was mostly above average, with seasonal totals in the range 30 to 80 mm.
  • Weak cold fronts and isolated thunderstorms produced mostly light rainfall across Greater Perth in December and January.
  • A tropical low (12U) produced widespread moderate rainfall on 7 and 8 February; daily rainfall of 38.4 mm on the 7th at Rottnest Island was the highest daily fall of this summer.
  • Perth Metro recorded a seasonal total of 43.2 mm, which was slightly higher than average, and wetter than the past 2 summers.

Above average daytime temperatures

  • The seasonal mean maximum temperatures were about 1 °C above average away from the Perth Hills, where daytime temperatures were near or slightly below average.
  • The seasonal mean minimum temperatures were mostly close to average, apart from Perth Airport, Pearce RAAF and Jandakot Airport, which were warmer than average.
  • December was particularly warm; Perth Metro had its second-warmest December on record, and Perth Airport had its equal second-warmest on record.
  • Perth Metro, Perth Airport, Pearce RAAF and Swan Valley recorded 3 consecutive days with temperatures over 40 °C, leading to a scorching Christmas Day.
  • Perth Metro recorded 42.2 °C on 8 January, which was its highest temperature this summer, and resulted in a count of 4 days of 40 °C this summer.
  • The coolest days were in early February between the 6th and 8th, with daily maxima dipping below 20 °C in the Perth Hills and on the islands.
  • The first December morning was the coldest morning this summer across Greater Perth, Perth Metro recorded a minimum temperature of 6.6 °C, which was 1.3 °C lower than its previous record.

Perth Metro

  • Total rainfall for Perth Metro was 43.2 mm, which is 101% of the long-term average of 42.6 mm.
  • The mean daily maximum temperature for Perth Metro was 31.6 °C, which is 0.9 °C above the long-term average of 30.7 °C.
  • The warmest day was 42.2 °C on 8 January, and the coolest day was on 7 February when the temperature reached 21.8 °C.
  • The mean daily minimum temperature for Perth Metro was 17.7 °C, which is 0.1 °C above the long-term average of 17.6 °C.
  • The coldest morning was 6.6 °C on 1 December, and the warmest morning was on 30 December when the minimum temperature was 24.1 °C.

Further information

Media
(03) 9669 4057

Extremes in summer 2020-21
Hottest day 42.6 °C at Pearce RAAF on 24 Dec 2020
Warmest days on average 33.2 °C at Pearce RAAF
Coolest days on average 27.2 °C at Rottnest Island
Coldest day 16.7 °C at Karnet on 6 Feb 2021
Coldest night 4.8 °C at Karnet on 1 Dec 2020
Coolest nights on average 15.1 °C at Bickley
15.1 °C at Karnet
Warmest nights on average 18.7 °C at Rottnest Island
Warmest night 26.7 °C at Mandurah on 9 Jan 2021
Warmest on average overall 25.4 °C at Pearce RAAF
Coolest on average overall 22.4 °C at Bickley
Wettest overall 87.1 mm at Huntly
Wettest day 45.0 mm at Midland on 14 Dec 2020
Strongest wind gust 94 km/h at Bickley on 6 Feb 2021

Record lowest summer temperature
New record
(°C)
Old
record
Years of
record
Average for
summer
Gosnells City 8.0 on 1 Dec 2020 = 8.0 on 2 Dec 2002 30 17.9
Perth Metro 6.6 on 1 Dec 2020 7.9 on 7 Dec 2007 28 17.6



Summary statistics for summer 2020-21
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
summer
2020-21
Diff
from
average
Highest for
summer
2020-21
Mean for
summer
2020-21
Diff
from
average
Lowest for
summer
2020-21
Total for
summer
2020-21
Average
for
summer
Rank of
summer
2020-21
Fraction of
summer
average
Bickley 29.8 0.0 39.1 25 Dec 2020 15.1 +0.1 6.5 1 Dec 2020 80.4 56.2 high 143%
Garden Island HSF 28.1 +1.1 39.5 8 Jan 2021 18.4 -0.2 11.2 1 Dec 2020 55.0 41.0 high 134%
Jandakot Aero 31.6 +0.9 41.3 8 Jan 2021 17.1 +0.9 5.0 1 Dec 2020 49.6 45.5 high 109%
Karnet 29.6 -0.2 38.6 25 Dec 2020 15.1 +0.2 4.8 1 Dec 2020 72.8 58.2 high 125%
Millendon (Swan Valley) 32.6   42.2 24 Dec 2020 17.3   6.2 1 Dec 2020 34.0
Pearce RAAF 33.2 +0.8 42.6 24 Dec 2020 17.6 +1.2 5.4 1 Dec 2020
Perth Airport 32.3 +1.4 41.7 24 Dec 2020 17.4 +0.9 4.9 1 Dec 2020 31.4 37.0 average 85%
Perth Metro 31.6 +0.9 42.2 8 Jan 2021 17.7 +0.1 6.6 1 Dec 2020 43.2 42.6 average 101%
Rottnest Island 27.2 +0.9 39.7 8 Jan 2021 18.7 0.0 12.8 1 Dec 2020 51.8 38.7 high 134%
Swanbourne 29.5 +0.2 40.1 8 Jan 2021 18.3 +0.4 9.0 1 Dec 2020 51.0 41.9 high 122%

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 3 pm on Monday 1 March 2021. 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

Climate