Greater Perth in August 2021: dry despite of above average numbers of rain day

August rainfall was below average across Greater Perth, and the Perth Metro site had the second-driest August on record. Both mean maximum and minimum temperatures were above average.

Below average rainfall

  • Monthly rainfall was 40–80% of August average at most sites, with August rainfall totals in the 50–90 mm range, to 100–160 mm in the Perth hills.
  • Perth Metro recorded 56.6 mm in total, which was the second-driest August on record at the Mount Lawley site, behind 2008 (27.8 mm); it was the eighth-driest August on record for the Perth city official records commencing in 1876.
  • Perth Metro recorded 17 days with daily rainfall of at least 0.2 mm, which was above its August average of 16 rain days; daily rainfall totals in 16 of 17 days were less than 10 mm, with the exception of 11.8 mm on the 20th.
  • Strong cold fronts produced damaging wind gusts in excess of 90 km/h recorded in Perth on the 1st and 10th; daily rainfall of 20-50 mm was recorded in the Perth hills on the 10th.

Above average temperatures

  • Mean maximum temperatures were 0.5–1.0 °C above average at most sites, but were close to average in the Perth hills.
  • The warmest days were on the 16th and 17th, with daily maximum temperatures mostly in the mid-20s.
  • Mean minimum temperatures were mostly 0.5–1.5 °C above average.
  • The warmest night was on the 17th with daily minima mostly in the mid-10s; Pearce RAAF had its highest daily minimum temperature in August on record.

Perth Metro

  • The mean daily maximum temperature for Perth Metro was 19.6 °C, which is 0.5 °C above the long-term average of 19.1 °C, although August 2021 was cooler than August 2020.
  • The warmest day was 25.1 °C on the 17th, and the coolest day was on the 10th when the temperature reached 14.4 °C.
  • The mean daily minimum temperature for Perth Metro was 9.3 °C, which is 1.0 °C above the long-term average of 8.3 °C, and the warmest August nights since 2017.
  • The coldest morning was 3.6 °C on the 6th, and the warmest morning was on the 9th when the minimum temperature was 13.8 °C.

Further information

Media
(03) 9669 4057

Extremes in August 2021
Hottest day 26.1 °C at Perth Airport on the 17th
Warmest days on average 19.6 °C at Perth Metro
Coolest days on average 16.0 °C at Bickley
Coldest day 10.3 °C at Bickley on the 1st
10.3 °C at Bickley on the 10th
Coldest night 2.1 °C at Jandakot Aero on the 2nd
Coolest nights on average 7.2 °C at Karnet
Warmest nights on average 12.6 °C at Rottnest Island
Warmest night 16.9 °C at Rottnest Island on the 17th
Warmest on average overall 15.6 °C at Rottnest Island
Coolest on average overall 12.0 °C at Bickley
Wettest overall 164.1 mm at Huntly
Wettest day 45.8 mm at Mount Solus on the 10th
Strongest wind gust 115 km/h at Rottnest Island on the 1st

 

Record highest August daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
August
Pearce RAAF 16.8 on the 17th 16.3 on the 7th in 2013 62 8.2



Summary statistics for August 2021
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
August
2021
Diff
from
average
Highest for
August
2021
Mean for
August
2021
Diff
from
average
Lowest for
August
2021
Total for
August
2021
Average
for
August
Rank of
August
2021
Fraction of
August
average
Bickley 16.0 0.0 22.8 17th 8.1 +0.5 4.5 24th 110.4 174.9 low 63%
Garden Island HSF 18.5 +0.4 24.4 16th 11.4 +0.2 6.0 2nd 67.0 94.3 v low 71%
Jandakot Aero 19.2 +0.5 25.3 16th 8.6 +1.4 2.1 2nd 79.8 127.3 low 63%
Karnet 16.3 +0.3 22.9 17th 7.2 +0.9 2.4 4th 135.0 183.3 low 74%
Mandurah 18.2 +0.1 25.0 16th 11.5 +0.5 6.5 2nd 48.6 93.1 v low 52%
Millendon (Swan Valley) 19.4   25.6 17th 8.7   2.7 2nd 66.2
Pearce RAAF 19.3 +0.9 25.5 17th 9.6 +1.4 3.9 2nd 86.0 105.6 low 81%
Perth Airport 19.5 +0.9 26.1 17th 9.2 +1.1 2.9 2nd 50.8 117.8 v low 43%
Perth Metro 19.6 +0.5 25.1 17th 9.3 +1.0 3.6 6th 56.6 122.0 v low 46%
Rottnest Island 18.6 +0.7 23.7 16th 12.6 +0.2 7.2 2nd 31.8 86.5 lowest 37%
Swanbourne 19.0 +0.1 25.3 16th 10.9 +0.8 6.0 5th 61.2 115.7 v low 53%

Daily maximum temperatures for August 2021
12345678910111213141516171819202122232425262728293031
Bickley10.312.813.916.016.419.516.816.315.110.313.514.417.218.419.021.322.817.714.416.215.214.814.917.921.115.714.214.315.415.2
Garden Island HSF14.816.217.316.719.620.919.019.818.614.617.815.719.217.622.124.421.319.019.018.018.016.118.420.921.418.316.217.319.318.219.3
Jandakot Aero14.616.117.218.819.522.319.119.719.614.117.317.220.220.022.625.324.018.719.118.417.417.921.023.718.817.417.719.419.119.7
Karnet10.913.214.217.920.117.915.110.414.914.217.617.819.322.522.918.017.815.414.614.615.518.516.214.514.716.516.2
Mandurah15.114.715.918.118.518.917.719.117.714.017.816.418.518.822.125.019.719.418.418.018.116.918.520.819.418.116.717.018.818.018.8
Millendon (Swan Valley)14.714.817.518.919.821.418.019.818.514.516.619.620.821.221.624.525.620.918.319.318.518.517.820.424.419.018.318.320.119.120.9
Pearce RAAF14.614.316.818.919.621.618.519.618.414.216.619.420.320.421.624.025.520.719.119.219.118.017.820.524.119.117.817.420.419.021.0
Perth Airport15.015.418.019.319.622.318.319.819.214.517.418.120.921.122.425.126.120.718.318.918.818.818.221.124.719.318.017.919.019.320.5
Perth Metro15.115.417.619.319.622.418.519.519.414.417.518.020.920.822.624.925.120.718.719.018.418.521.124.719.517.818.719.419.920.5
Rottnest Island15.315.416.817.819.020.719.519.819.114.918.216.618.717.620.423.722.119.818.718.618.616.517.320.120.918.817.417.419.018.719.5
Swanbourne14.515.617.317.819.722.319.219.618.914.317.718.219.718.622.925.321.319.018.419.318.317.718.321.122.618.617.617.419.119.219.7
Values are the maximum temperature, usually in the 24 hours from 9 am on the day indicated,
and typically occurred in the afternoon of that day.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily minimum temperatures for August 2021
12345678910111213141516171819202122232425262728293031
Bickley7.05.57.56.65.05.79.710.010.86.95.37.96.58.77.37.911.612.49.88.99.48.34.94.56.610.57.47.09.910.911.6
Garden Island HSF10.96.09.67.07.48.912.413.914.811.09.811.07.97.110.613.314.212.311.813.114.413.39.19.713.014.813.810.013.214.415.1
Jandakot Aero9.22.17.55.03.22.56.812.213.810.15.88.03.52.86.413.014.010.09.410.010.211.25.97.210.810.710.87.412.213.812.2
Karnet4.47.53.52.43.56.211.06.83.97.55.93.06.69.512.011.98.07.48.78.44.05.59.06.55.010.511.411.7
Mandurah9.86.59.28.07.98.813.414.114.210.69.411.810.18.610.612.316.214.312.813.113.313.18.38.912.913.811.610.813.014.114.9
Millendon (Swan Valley)9.62.77.85.34.23.69.711.912.610.55.57.84.93.47.311.715.212.87.210.38.99.76.47.612.612.76.36.411.011.211.7
Pearce RAAF9.73.99.07.26.95.512.611.713.09.35.89.77.63.98.413.416.812.48.010.09.111.57.69.011.712.19.08.511.111.612.3
Perth Airport9.52.98.64.95.68.210.511.413.19.86.48.47.93.38.510.815.913.28.010.09.29.86.18.411.712.28.76.711.412.711.9
Perth Metro9.73.78.86.33.83.66.511.813.89.76.89.05.14.17.111.113.311.39.811.49.712.15.37.812.612.512.69.412.113.712.9
Rottnest Island10.77.210.712.111.212.314.714.513.810.58.712.012.212.612.113.516.915.514.613.813.413.210.410.813.013.912.212.213.614.014.2
Swanbourne9.56.28.68.06.06.911.512.613.69.78.310.47.87.59.312.916.213.411.111.914.313.27.38.912.114.113.210.413.614.414.4
Values are the minimum temperature, usually in the 24 hours to 9 am on the day indicated,
and typically occurred that morning.
Temperatures coloured according to their difference
from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C Grey outline marks highest
and lowest for the period

Daily rainfall for August 2021
12345678910111213141516171819202122232425262728293031
Anketell 10.6 6.4 0.2 - - - - 1.1 5.9 14.7 3.8 1.8 0.2 - - - - - 4.2 12.3 5.9 1.7 0.1 - - 1.6 5.2 0.8 2.3 6.3 2.7
Bickley 21.2
1.4 - - 0.2 - 5.4 12.8 21.2 8.0 0.4 0.2 - 0.2 - 0.2 0.2 0.8 10.6 1.6 3.2 0.2 - - 3.0 5.4 - 3.2 7.6 3.4
Bungendore 11.4 4.0 0.2 0.2 0.2 0.2 - 2.4 11.0 20.8 3.8 1.4 0.4 0.2 - - - - 2.2 7.8 4.0 2.6 0.2 - - 1.8 4.4 - 2.0 5.8 3.4
Chidlow 20.1 0.2 - - - - 17.2 26.2 5.1 0.6 - - - - - 0.2 0.2 5.0 0.1 3.2 - - 0.8 1.5 - 4.4 2.1
Garden Island HSF 7.2 2.8 - 0.2 - - - 1.4 4.2 9.6 3.0 1.8 2.2 0.2 - - - - 4.4 16.4 2.8 0.2 - - - 2.0 0.4 0.6 2.0 4.6 1.0
Gidgegannup 18.4 2.4 - - - - - 3.6 11.6 19.8 5.0 0.4 - - 0.2 - - 0.2 0.2 12.6 1.0 3.2 - - - 0.8 2.2 - 0.8 2.8 3.8
Huntly 29.8 6.8 0.4 - - - - 3.2 15.1 35.0 7.0 1.2 0.2 - - - 0.6 - 7.0 4.2 6.6 4.4 - - - 6.4 7.6 1.0 7.0 12.0 8.6
Jandakot Aero 9.6 4.8 0.2 - - - - 1.6 8.4 12.8 5.4 0.8 0.2 - - - - 2.4
11.2 2.4 3.0 - - - 3.4 3.6 0.2 1.2 4.2 4.4
Jarrahdale 13.6 5.0 0.2 0.4 - 0.4 - 1.2 16.0 21.4 8.0 5.4 1.4 0.4 0.2 - - - 2.4 20.6 7.0 6.4 0.2 0.2 - 2.6 7.0 - 7.2 12.2 8.0
Karnet 19.5 4.1 - - - - - 16.8 31.0 8.4 2.2 3.6 - - - - 0.1 7.4 5.8 3.8 7.5 - - -
0.8 - 6.0 10.2 7.8
Karragullen North 17.2 5.6 0.2 - - - - 4.6 12.6 31.8 9.8 - - - - - - 1.8 0.6 13.4 3.0 3.4 - - - 3.4 4.6 0.1 1.4 6.4 4.0
Maida Vale 14.2 3.6 - - - - - 4.4 5.0 9.2 9.4 1.0 - - - - - - 2.0 17.8 0.8 1.0 - - - 2.0 1.6 - 2.6 2.6 2.0
Mandurah 5.2 - 0.6 - - - - 3.0 1.2 4.2 3.0 3.8 - - - - - - 8.4 0.6 3.0 1.4 - - - 2.2 2.4 1.0 5.6 2.4 0.6
Millendon (Swan Valley) 9.4 5.4 - - - - - 4.2 3.0 15.2 6.6 0.6 0.2 - - - - 1.2 0.8 9.0 1.6 1.4 - - - 0.8 2.4 - 0.4 2.8 1.2
Mount Solus 16.0 5.6 0.2 - 0.2 - - 1.2 15.0 45.8 7.2 2.0 3.2 0.2 - - - - 7.0 10.6 2.6 5.8 0.2 - 0.2 2.2 6.0 0.4 3.4 11.8 5.4
Muchea 11.8 5.2 - - - - 0.2 4.4 7.6 21.6 5.0 1.2 0.2 - - 0.2 - 0.4 0.2 19.8 0.2 1.4 - - - 1.6 3.6 0.2 0.6 1.8 0.4
Mundaring 11.0 4.8 0.4 - - - - 5.2 12.0 19.6 6.2 - - - - - - 2.0 0.8 7.0 4.3 - - - 2.0 6.2 - 2.6 - 2.8
Pearce RAAF 16.2 7.0 - - - - - 3.2 10.6 16.0 5.2 0.4 0.2 - - - - - 0.2 19.6 - 1.2 0.4 - - 0.8 2.6 - 0.2 1.8 0.4
Perth Airport 9.0 0.8 - - - - - 3.8 4.0 10.0 3.2 0.8 - - - - - 0.4 1.4 8.4 0.2 0.6 - - - 1.6 1.6 0.2 2.0 2.0 0.8
Perth Metro 8.8 2.6 - - - - - 3.8 5.2 6.4 4.2 1.2 - - - - 0.2 1.2 1.0 11.8
0.8 - - - 0.6 2.4 - 2.4 2.8 1.2
Pinjarra South 18.6 3.6 0.4 - - - - 0.8 9.4 15.4 6.6 2.0 - - - - - - 8.0 1.6 5.2 1.4 - - - 2.4 4.2 0.6 4.2 5.4 0.6
Roleystone 17.6 5.6 - - - - - 4.8 13.8 21.8 7.6 2.0 - - - - - 0.8 0.8 15.0 4.0 - - - - 5.4 - 5.0 3.4 4.2
Rottnest Island 2.0 5.2 1.6 0.2 - - - 1.2 3.4 5.2 1.8 1.0 0.4 0.2 - - - - 0.4 2.2 0.4 0.8 0.2 - - 1.2 0.6 0.2 1.8 0.2 1.6
Serpentine 13.0 4.2 - 0.2 - - - 0.2 5.4 13.4 5.0 9.2 1.0 - - - 0.4 - 3.2 8.8 5.6 3.6 0.2 - - 2.4 3.6 0.2 7.8 7.6 4.2
Swanbourne 8.4 2.8 0.4 - - - - 3.6 3.2 10.8 3.8 1.8 0.2 - - - - 0.6 4.8 13.0 0.6 0.6 - - - 1.2 1.4 0.2 1.2 1.2 1.4
Tamala Park (Mindarie) 6.4 4.4 0.2 - - - - 4.4 2.2 13.8 2.2 0.5 - - - - - 2.8 9.4 17.2 0.2 2.0 - - - 1.6 1.6 0.2 - 1.4 1.2
Wanneroo 22.0 - - - 6.6 20.2 4.4 0.8 0.2 - - - 0.5 2.2 - 25.4 - - 1.4 - - 2.4 4.0 3.8
Werribee 16.8 3.0 0.6 - - 0.2 - 3.2 11.6 20.0 7.0 0.2 0.4 - 0.2 - - - 0.2 5.8 0.2 2.0 0.2 - - 0.2 1.6 - 0.2 2.6 2.6
Rainfalls coloured
according to the amount
0 1.0 5.0 10.0 15.0 25.0 50.0 100 150 200 300 400 600 millimetres

Notes

The Monthly 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 Wednesday 1 September 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