Greater Perth in July 2021: wettest July for decades

July 2021 was the wettest July in decades across Greater Perth. Mean minimum temperatures were one and half degrees to three degrees warmer than average at most locations.

Very wet across Greater Perth

  • July 2021 was very wet across Greater Perth, with monthly rainfall totals the 240–310 mm range, and up to 400–460 mm in the Perth hills.
  • Many sites had their wettest July on record or wettest July for more than 20 years.
  • Bickley recorded 459.2 mm, which is its annual highest monthly total; the last time that Greater Perth saw July rainfall totals of 400 mm was in 1964.
  • Perth Airport and Jarrahdale had their wettest July since 1958, and several sites in the Perth hills had their wettest July since 1964.
  • Perth Metro recorded 271.4 mm in total, which was the second-wettest July on record at the site, behind 278.6 mm in 1995; it was the 10th-wettest July on record in the official Perth records commencing in 1876.
  • Perth Metro recorded rainfall of 0.2 mm or higher in 28 of 31 days, which was the highest count of rain days in July on record at the site, and the second-highest count in July on record in the official Perth records, behind 29 days in 1946.
  • Perth Metro recorded 18 consecutive days with daily rainfall of 0.6 mm or higher between the 4th and 21st, which was the longest such spell for any month since 18 consecutive days in 1996 (between 21 July and 7 August).
  • Rainfall in excess of 20 mm was recorded on the 5th, 7th, 10th, 21st and 27th at most sites; falls of 60 mm-80 mm were recorded in the Perth hills on the 27th, including a number of July daily rainfall records

Warmer than normal nights

Perth Metro

  • Total rainfall for Perth Metro was 271.4 mm, which is 185% of the long-term average of 146.8 mm
  • The mean daily maximum temperature for Perth Metro was 18.3 °C, which is 0.2 °C below the long-term average of 18.5 °C
  • The warmest day was 21.7 °C on the 12th, and the coolest day was on the 4th when the temperature reached 15.9 °C
  • The mean daily minimum temperature for Perth Metro was 10.6 °C, which is 2.7 °C above the long-term average of 7.9 °C
  • The coldest morning was 4.4 °C on the 3rd, and the warmest morning was on the 13th when the minimum temperature was 13.9 °C

Further information

Media
(03) 9669 4057

Extremes in July 2021
Hottest day 21.9 °C at Gosnells City on the 30th
Warmest days on average 18.3 °C at Millendon (Swan Valley)
18.3 °C at Perth Airport
18.3 °C at Perth Metro
18.3 °C at Rottnest Island
Coolest days on average 14.6 °C at Bickley
Coldest day 11.6 °C at Karnet on the 20th
11.6 °C at Karnet on the 30th
Coldest night 3.4 °C at Jandakot Aero on the 3rd
Coolest nights on average 8.7 °C at Bickley
Warmest nights on average 13.1 °C at Rottnest Island
Warmest night 17.3 °C at Garden Island HSF on the 26th
Warmest on average overall 15.7 °C at Rottnest Island
Coolest on average overall 11.7 °C at Bickley
Wettest overall 459.2 mm at Bickley
Wettest day 77.0 mm at Huntly on the 27th
Strongest wind gust 113 km/h at Rottnest Island on the 6th
113 km/h at Pearce RAAF on the 26th

Record highest July daily rainfall
New record
(mm)
Old
record
Years of
record
Huntly 77.0 on the 27th 60.8 on the 22nd in 2004 32
Anketell 67.2 on the 27th 53.4 on the 5th in 2019 20



Record highest July total rainfall
New record
(mm)
Old
record
Years of
record
Average for
July
Pearce RAAF 247.0 242.6 in 1995 67 134.5
Roleystone 391.9 381.1 in 1964 54 201.2
Bickley 459.2 364.4 in 2000 53 219.7
Karragullen North 418.2 414.3 in 1964 48 205.6
Jandakot Aero 315.0 284.6 in 1974 47 174.7
Maida Vale 290.8 278.2 in 1978 39 162.2
Pinjarra Refinery 285.7 273.2 in 2000 37 158.8
Huntly 430.2 381.9 in 2000 29 230.8
Swanbourne 285.4 240.0 in 1995 28 152.0
Pinjarra South 218.2 184.6 in 2003 21 127.2
Anketell 346.7 233.4 in 2008 20 160.5
Werribee 263.6 157.6 in 2018 20 115.1

Highest July total rainfall for at least 20 years
Observed
(mm)
Most recent
higher
Average for
July
Perth Airport 251.2 446.7 in 1958 155.5
Jarrahdale 443.8 520.9 in 1958* 226.9
Chidlow 336.2 340.9 in 1964* 177.8
Gidgegannup 304.2 408.8 in 1964* 179.8
Serpentine 312.4 316.8 in 1964* 180.5
Perth Metro 271.4 278.6 in 1995 146.8

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




Record highest July daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
July
Garden Island HSF 17.3 on the 26th 17.0 on the 4th in 2002 20 11.3
Mandurah 16.7 on the 26th 16.4 on the 31st in 2015 20 10.7



Record highest July mean daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
July
Jandakot Aero 10.1 9.7 in 2017 31 7.0
Perth Metro 10.6 = 10.6 in 1996 27 7.9
Swanbourne 11.8 11.6 in 2007 27 9.8

Highest July mean daily minimum temperature for at least 20 years
Observed
(°C)
Most recent
higher
Average for
July
Perth Airport 10.2 10.5 in 1996 8.0



Summary statistics for July 2021
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
July
2021
Diff
from
average
Highest for
July
2021
Mean for
July
2021
Diff
from
average
Lowest for
July
2021
Total for
July
2021
Average
for
July
Rank of
July
2021
Fraction of
July
average
Bickley 14.6 -0.5 17.3 3rd 8.7 +1.4 5.1 31st 459.2 219.7 highest 209%
Garden Island HSF 18.0 +0.1 20.5 3rd 12.8 +1.5 8.7 3rd 239.6 122.9 v high 195%
Jandakot Aero 18.1 +0.1 21.3 12th 10.1 +3.1 3.4 3rd 315.0 174.7 highest 180%
Mandurah 17.5 0.0 19.6 12th 12.2 +1.5 8.0 31st        
Millendon (Swan Valley) 18.3   21.1 12th 9.7   5.1 3rd 248.8
Pearce RAAF 18.0 +0.1 20.8 12th 10.2 +1.8 5.4 22nd 247.0 134.5 highest 184%
Perth Airport 18.3 +0.3 21.4 12th 10.2 +2.2 5.0 22nd 251.2 155.5 v high 162%
Perth Metro 18.3 -0.2 21.7 12th 10.6 +2.7 4.4 3rd 271.4 146.8 v high 185%
Rottnest Island 18.3 +0.5 20.6 12th 13.1 +0.7 10.1 31st 166.6 112.8 v high 148%
Swanbourne 18.0 -0.4 20.7 3rd 11.8 +2.0 8.2 3rd 285.4 152.0 highest 188%

Daily maximum temperatures for July 2021
12345678910111213141516171819202122232425262728293031
Bickley15.916.217.312.212.814.613.915.015.514.215.017.215.014.313.314.915.013.714.314.515.514.814.913.716.614.713.114.715.912.211.7
Garden Island HSF17.717.820.518.517.318.917.618.517.416.918.520.218.817.317.218.017.918.217.715.417.317.018.118.019.519.616.418.519.615.916.6
Jandakot Aero18.018.220.716.317.019.518.218.819.217.118.621.319.717.417.617.818.018.017.313.718.217.718.217.520.119.016.818.720.516.215.8
Karnet15.815.618.613.616.216.514.016.617.916.014.514.115.216.415.015.811.614.014.214.215.617.116.113.614.617.211.612.7
Mandurah17.817.118.818.016.918.417.418.317.716.617.819.618.317.617.017.417.717.416.913.717.016.817.117.518.918.616.217.719.115.516.2
Millendon (Swan Valley)19.219.819.816.517.518.417.618.418.617.618.221.119.618.117.517.117.817.317.117.418.818.119.018.620.318.816.819.120.116.015.9
Pearce RAAF18.519.420.216.316.917.617.518.118.717.318.220.819.216.917.617.017.617.917.117.618.517.118.818.520.218.916.118.420.116.315.3
Perth Airport18.219.020.315.417.119.717.918.919.217.318.721.419.117.918.317.418.217.617.116.918.317.518.818.220.019.116.719.220.516.616.0
Perth Metro19.518.920.015.916.819.517.818.719.318.018.321.718.918.317.917.418.018.117.016.118.517.819.118.120.218.716.919.120.616.316.2
Rottnest Island19.119.020.019.117.419.318.518.920.017.818.320.619.217.617.819.017.917.818.115.917.516.818.317.819.919.616.618.619.815.616.6
Swanbourne18.118.820.717.317.119.317.919.218.817.118.620.618.817.317.417.317.117.817.414.417.417.018.518.119.918.416.718.719.816.116.4
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 July 2021
12345678910111213141516171819202122232425262728293031
Bickley9.27.55.67.48.08.38.59.410.26.48.38.512.010.28.78.99.810.08.610.010.36.87.98.010.210.39.97.79.68.95.1
Garden Island HSF12.710.98.713.113.513.513.314.114.410.511.413.814.914.314.013.912.812.613.313.112.98.911.713.515.317.312.912.112.712.69.2
Jandakot Aero6.93.410.09.18.511.710.411.75.38.812.313.612.512.410.611.59.08.511.311.65.210.410.211.011.213.110.611.912.67.2
Karnet8.46.08.87.96.58.75.79.812.210.69.07.610.07.06.59.610.25.58.46.29.711.65.89.99.03.5
Mandurah12.110.69.211.313.213.512.513.913.98.711.112.715.114.611.012.512.912.911.612.412.38.610.412.914.316.712.612.412.612.68.0
Millendon (Swan Valley)10.66.05.110.88.77.18.98.110.56.98.913.313.99.711.610.910.68.97.611.512.55.69.28.311.810.513.29.312.412.66.8
Pearce RAAF11.07.08.112.49.18.810.09.410.38.58.913.213.110.511.29.910.99.59.011.812.65.48.38.811.211.112.69.912.912.08.1
Perth Airport10.69.17.211.98.97.811.57.911.26.110.613.113.69.511.711.311.710.07.911.812.55.010.38.711.111.013.09.511.912.77.0
Perth Metro10.77.94.49.78.89.111.810.111.77.59.811.613.913.312.811.811.810.89.111.812.66.110.59.811.812.013.510.711.812.57.9
Rottnest Island13.713.912.714.212.113.212.513.514.211.911.714.314.913.612.713.612.212.514.112.812.811.913.413.813.416.812.412.213.512.310.1
Swanbourne11.09.28.211.113.011.412.713.612.99.810.712.714.314.112.412.211.911.410.611.912.68.510.513.213.214.913.710.911.912.39.5
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 July 2021
12345678910111213141516171819202122232425262728293031
Anketell 0.4 0.9 0.2 6.4 29.0 6.6 32.2 3.9 1.9 42.4 0.6 15.4 13.2 11.8 11.5 3.6 1.6 7.1 3.9 0.5 45.2 0.2 1.4 5.6 0.5 0.4 67.2 2.2 11.2 9.5 10.2
Bickley 2.8 - 0.4 1.8 50.2 11.4 43.4 6.0 6.8 37.6 - 18.0 30.0 23.8 21.2 2.8 2.0 8.4 5.2 3.8 52.2 0.2 1.4 5.6 0.8 0.2 59.8 4.2 23.2 25.0 11.0
Bungendore 3.6 - - 0.8 44.0 8.6 41.4 5.6 3.0 63.2 - 16.0 19.0 22.4 14.8 2.2 2.2 4.8 7.8 0.4 41.8 0.2 0.6 6.8 1.0 0.6 55.0 3.0 15.8 21.4 16.2
Chidlow 0.4 - - 36.8 6.0 32.8 5.2 7.8 26.3 13.6 46.6 22.5 15.5 - 2.4 4.8 3.0 29.8 2.0 1.0 0.2 37.6 3.4 7.6 20.2 10.7
Garden Island HSF 0.4 1.0 - 4.0 19.8 7.2 8.4 1.0 6.2 29.8 2.2 16.8 5.6 5.6 2.4 4.6 1.6 15.0 0.8 0.4 37.0 - 0.6 2.4 - - 35.4 5.0 13.4 5.4 7.6
Gidgegannup 0.6 0.6 - - 34.4 7.8 28.6 9.2 8.6 25.6 - 12.4 27.6 17.6 12.0 5.6 0.8 0.2 12.6 2.2 23.4 0.2 1.0 1.4 1.4 - 29.8 3.2 12.4 12.8 12.2
Huntly 3.0 2.0 - 8.0 48.0 19.0 14.0 12.0 3.0 42.3 - 19.0 22.0 16.0 19.4 4.0 2.0 10.0 4.0 1.8 31.5 1.0 2.0 13.4 1.5 1.2 77.0 3.0 30.8 10.0 9.3
Jandakot Aero
- - 8.4 31.0 9.0 22.2 2.0 4.8 32.8 0.2 16.4 6.8 9.6 8.0 6.4 0.4 6.8 10.6 0.6 46.4 - 1.4 2.8 0.2 0.2 47.4 2.0 21.6 3.8 13.2
Jarrahdale 1.0 - 0.2 1.0 37.2 9.2 50.0 4.2 5.6 48.4 - 19.6 21.4 20.4 17.2 1.8 2.8 6.4 3.0 0.8 53.0 0.2 1.4 7.2 2.2 0.4 75.4 4.0 18.8 16.8 14.2
Karragullen North 1.6 - - - 54.6 9.6 54.0 1.4 7.0 46.6 - 17.0 12.2 19.0 14.6 1.8 2.2 12.0 4.8 1.8 48.6 - 1.2 6.0 - 0.6 48.0 3.8 18.2 16.2 15.4
Maida Vale 1.0 - - 4.4 42.8 12.2 28.4 2.2 - 27.2 0.2 10.4 21.2 10.4 13.2 4.4 4.4 3.4 3.8 1.8 21.8 0.4 3.2 3.6 0.6 0.4 33.0 5.6 10.4 16.0 4.4
Millendon (Swan Valley) 0.4 0.4 - 1.8 36.0 5.6 27.2 6.0 9.6 26.2 - 10.8 19.4 6.4 8.0 7.8 1.0 0.4 3.8 0.4 18.2 - 1.0 1.4 0.8 - 28.8 2.8 7.8 11.8 5.0
Mount Solus 0.2 0.4 0.2 2.6 32.8 7.2 32.0 5.0 5.2 43.8 0.2 19.2 24.4 23.8 18.4 1.4 0.2 2.4 4.4 1.6 56.0 0.6 1.0 7.2 1.8 0.4 73.4 1.8 20.0 18.6 13.8
Muchea - 0.8 - 0.4 30.6 5.2 42.2 2.0 6.2 17.8 - 12.4 27.4 6.6 13.2 3.2 1.4 1.2 6.8 0.4 11.2 - 2.0 0.8 0.6 - 32.0 4.6 8.0 11.0 6.6
Mundaring 1.0 0.2 - 5.0 37.0 7.6 28.4 3.4 11.0 28.2 0.2 12.2 32.0 21.4 22.4 2.4 - 2.6 11.4 3.2 29.0 - 3.8 2.2 0.4 - 41.0 5.6 - 16.2 9.2
Pearce RAAF 0.4 0.2 - 0.4 31.4 5.4 29.2 1.4 7.4 22.4 0.8 12.6 14.2 16.0 8.6 2.4 1.4 1.4 8.8 0.2 13.2 - 2.2 0.4 0.6 - 23.8 4.8 9.4 21.6 6.4
Perth Airport 0.6 0.2 - 3.6 35.4 11.2 22.2 4.0 4.6 18.8 - 8.6 23.4 13.0 7.0 5.0 1.0 0.6 4.0 1.0 23.0 - 1.6 0.2 - - 27.8 4.4 8.0 14.6 7.4
Perth Metro 1.4 - - 1.4 44.6 7.4 23.6 4.6 4.2 30.0 0.6 9.6 13.4 14.0 2.0 13.4 2.8 1.2 5.4 1.6 29.6 - 1.8 2.0 0.6 0.2 30.4 5.8 6.4 7.0 6.4
Pinjarra Refinery 1.0 0.2 - 5.4 31.8 8.2 7.8 5.8 6.4 28.4 0.4 17.2 18.2 10.0 9.0 4.2 0.6 12.2 4.8 0.8 11.8 0.4 1.4 7.6 0.4 0.6 48.1 3.6 24.0 7.4 8.0
Pinjarra South 1.4 0.6 0.2 3.4 23.4 8.2 6.0 5.4 3.4 18.4 0.2 9.2 17.0 9.8 7.4 1.6 1.2 4.6 4.2 - 14.4 - - 8.0 0.2 - 39.0 0.6 19.2 3.6 7.6
Roleystone 1.2 - - - 42.0 4.2 37.6 1.6 7.2 58.2 - 14.8 27.9 12.2 15.0 2.2 2.6 3.4 4.4 1.4 39.8 - 1.0 6.2 0.6 1.0 61.4 3.8 13.8 10.0 18.4
Rottnest Island 2.0 0.2 - 3.6 17.2 1.6 12.8 0.4 2.8 8.6 5.2 12.6 2.6 3.6 0.8 0.8 8.0 8.2 0.8 1.0 31.8 0.4 0.4 - - - 28.2 1.2 5.2 5.4 1.2
Serpentine 1.0 0.2 0.2 3.8 30.6 5.8 29.0 4.0 6.4 45.4 0.2 15.6 8.0 11.2 10.6 1.6 3.0 8.2 2.4 0.2 39.6 - 0.4 3.6 1.2 0.4 43.8 3.6 9.6 12.6 10.2
Swanbourne 1.8 - - 10.4 29.6 7.4 17.6 2.4 11.2 30.8 0.2 13.2 6.0 5.4 5.4 8.8 4.4 15.2 14.0 0.8 34.6 0.4 2.4 0.2 - - 37.2 4.4 8.6 10.2 2.8
Wanneroo 3.6 0.3 64.6 19.6 0.8 11.4 30.6 12.6 4.8 6.6 9.8 13.0 2.6 30.0 0.4 - 3.4 17.4 4.8 8.2 4.4
Werribee 0.6 - 0.2 0.2 40.6 2.0 22.4 3.8 5.6 26.4 - 14.4 25.8 7.0 12.4 0.6 0.6 1.4 4.0 2.6 18.8 - 1.0 1.2 1.0 - 34.0 1.6 10.0 14.2 11.2
Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with → are part of a longer accumulation, which is shown on the final day.
Values over 100 mm have been rounded to the nearest whole millimetre.
Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
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 4 pm on Sunday 1 August 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

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