Greater Perth in December 2019: very hot first half of December

Daytime and overnight temperatures were well above average across Greater Perth, and it was the warmest December on record for most sites. It was particularly hot during the first half of December, and Perth Metro had four days with temperatures over 40 degree. Monthly rainfall was below average across Perth.

Below average rainfall

  • Monthly rainfall totals were generally less than 5 mm, and up to about 10 mm along the Perth hills
  • There were two wet days as a pair of weak cold fronts produced light rainfall in the 24 hours to 9am on the 8th and 20th

Above average temperatures across Perth

  • It was the warmest December on record for most sites in terms of mean temperatures
  • Mean maximum temperatures were 2-5 °C above average across Greater Perth, and several sites had their warmest December on record
  • Perth Metro's mean maximum temperature was 33.1 °C, which was its December record and 1.7 °C higher than its previous December record in 1999
  • Prior to this December, mean maximum temperatures in December at Perth city had not reached 32 °C since record commenced in 1897, the previous highest was 31.7 °C in 1931 recorded at Perth Regional Office
  • The first half of December was particularly hot, and Perth Metro had two spells with temperature over 35 °C: between the 2nd and 6th, and between the 10th and 16th
  • Perth Metro and Perth Airport not only recorded their first run of three consecutive days of over 40 °C (between the 13th and 15th) in December, but also doubled their previous record count of 40 °C days with four and eight respectively
  • Mean minimum temperatures were 2-3 °C above average across Perth, and several sites excessed their previous December record set in 2011
  • Perth Metro's mean maximum temperature was 18.3 °C, which just exceeded its previous December record at 18.2 °C in 2011

Perth Metro

  • Total rainfall for Perth Metro was 2.4 mm, which is 23% of the long-term average of 10.6 mm
  • The mean daily maximum temperature for Perth Metro was 33.1 °C, 4.0 °C above the long-term average of 29.1 °C. The warmest day was 41.6 °C on the 3rd, and the coolest day was on the 30th when the temperature reached 24.9 °C
  • The mean daily minimum temperature for Perth Metro was 18.3 °C, 2.0 °C above the long-term average of 16.3 °C. The coldest morning was 12.9 °C on the 31st, and the warmest morning was on the 6th when the minimum temperature was 24.6 °C

Further information

Media
(03) 9669 4057
Enquiries

Extremes in December 2019
Hottest day 43.9 °C at Pearce RAAF on the 15th
Warmest days on average 35.5 °C at Pearce RAAF
Coolest days on average 28.0 °C at Garden Island HSF
Coldest day 20.7 °C at Bickley on the 19th
Coldest night 9.6 °C at Bickley on the 1st
Coolest nights on average 16.5 °C at Bickley
Warmest nights on average 20.1 °C at Mandurah
Warmest night 27.1 °C at Pearce RAAF on the 6th
Warmest on average overall 26.2 °C at Pearce RAAF
Coolest on average overall 23.8 °C at Garden Island HSF
Wettest overall 11.0 mm at Jarrahdale
Driest overall 0.4 mm at Mandurah
Wettest day 9.8 mm at Huntly on the 20th
Strongest wind gust 76 km/h at Pearce RAAF on the 10th

Record highest December mean daily maximum temperature
New record
(°C)
Old
record
Years of
record
Average for
December
Perth Airport 33.9 32.4 in 1999 75 29.0
Pearce RAAF 35.5 34.1 in 1972 59 30.4
Jandakot Aero 32.8 31.5 in 2009 29 29.1
Rottnest Island 28.1 27.8 in 1999 28 25.0
Bickley 31.9 30.3 in 2009 25 28.1
Perth Metro 33.1 31.4 in 1999 25 29.1

Highest December mean daily maximum temperature for at least 20 years
Observed
(°C)
Most recent
higher
Average for
December
Karnet 31.8 32.6 in 1993 28.1
Swanbourne 30.3 30.5 in 1999 27.8



Record highest December mean daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
December
Jandakot Aero 17.7 16.7 in 2011 29 14.7
Rottnest Island 19.8 19.0 in 2011 28 17.6
Swanbourne 19.5 18.3 in 2011 26 16.5
Bickley 16.5 15.4 in 2012 25 13.6
Perth Metro 18.3 18.2 in 2011 25 16.3

Highest December mean daily minimum temperature for at least 20 years
Observed
(°C)
Most recent
higher
Average for
December
Perth Airport 17.7 17.8 in 1977 14.9



Record highest December mean temperature
New record
(°C)
Old
record
Years of
record
Average for
December
Perth Airport 25.8 24.8 in 1999 75 22.0
Pearce RAAF 26.2 25.1 in 1977 59 22.5
Jandakot Aero 25.3 24.0 in 1999 29 21.9
Rottnest Island 23.9 23.4 in 1999 28 21.3
Swanbourne 24.9 24.1 in 2011 26 22.2
Bickley 24.2 22.3 in 2012 25 20.9
Perth Metro 25.7 24.6 in 1999 25 22.7



Summary statistics for December 2019
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
December
2019
Diff
from
average
Highest for
December
2019
Mean for
December
2019
Diff
from
average
Lowest for
December
2019
Total for
December
2019
Average
for
December
Rank of
December
2019
Fraction of
December
average
Bickley 31.9 +3.8 39.6 15th 16.5 +2.9 9.6 1st 8.0 14.6 average 55%
Garden Island HSF 28.0 +2.6 38.3 13th 19.7 +2.5 13.8 1st 1.4 10.4 low 13%
Jandakot Aero 32.8 +3.7 40.4 13th 17.7 +3.0 11.3 9th 3.8 10.6 average 36%
Karnet 31.8 +3.7 38.0 15th     10.2 1st 8.2 18.8 average 44%
Mandurah 30.3 +3.3 39.5 12th 20.1 +3.0 13.3 1st 0.4 15.9 v low 3%
Millendon (Swan Valley) 34.6   42.2 15th 16.9   11.1 9th 2.8
Pearce RAAF 35.5 +5.1 43.9 15th 16.9 +2.4 10.6 9th 0.8 10.9 low 7%
Perth Airport 33.9 +4.9 41.6 15th 17.7 +2.8 12.1 28th 2.2 11.2 low 20%
Perth Metro 33.1 +4.0 41.6 3rd 18.3 +2.0 12.9 31st 2.4 10.6 low 23%
Rottnest Island 28.1 +3.1 37.9 13th 19.8 +2.2 14.9 1st 1.8 10.9 low 17%
Swanbourne 30.3 +2.5 39.3 13th 19.5 +3.0 14.0 31st 2.8 11.1 average 25%

Daily maximum temperatures for December 2019
12345678910111213141516171819202122232425262728293031
Bickley30.032.737.736.737.637.123.924.328.733.434.936.237.938.439.637.736.233.820.724.832.428.131.434.034.730.028.428.723.924.729.2
Garden Island HSF28.133.037.726.030.834.825.021.623.427.737.837.238.329.228.926.626.129.324.426.329.623.124.327.426.725.623.823.725.421.823.9
Gosnells City33.536.040.541.040.127.228.031.037.038.040.536.535.527.534.129.632.836.630.028.529.326.526.130.6
Jandakot Aero33.435.140.337.040.339.526.425.229.535.838.038.640.439.339.738.234.933.525.025.832.627.330.532.234.328.027.427.026.025.229.0
Karnet30.833.437.837.037.524.024.028.533.634.437.338.037.135.433.827.231.734.634.630.130.527.823.424.328.2
Mandurah31.633.835.633.136.433.124.423.326.633.539.039.535.137.034.134.333.029.623.826.429.725.728.030.831.824.725.725.025.023.625.9
Millendon (Swan Valley)33.235.941.438.940.441.328.126.831.836.238.039.140.941.942.239.837.036.024.927.535.730.333.836.237.931.130.130.427.327.131.7
Pearce RAAF33.736.842.240.341.541.928.928.132.437.239.039.740.942.543.940.738.237.226.128.636.331.135.536.539.432.331.030.828.427.632.9
Perth Airport33.136.140.938.040.740.927.226.031.437.038.039.240.640.941.639.335.635.024.727.234.929.332.334.236.729.429.128.726.926.230.8
Perth Metro32.935.641.637.639.238.926.525.129.936.337.639.040.141.040.938.534.325.125.834.528.431.032.535.728.527.327.425.824.929.6
Rottnest Island25.831.137.226.030.035.424.922.923.926.230.535.637.933.332.028.927.230.824.224.528.324.625.725.528.325.425.624.625.623.424.6
Swanbourne30.035.038.832.935.336.525.223.625.330.238.338.939.337.636.831.728.329.524.725.232.225.927.326.931.126.026.025.025.923.925.6
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 December 2019
12345678910111213141516171819202122232425262728293031
Bickley9.615.219.222.318.720.216.011.912.214.414.516.120.321.221.121.921.119.316.913.714.116.116.116.417.817.615.312.714.811.712.9
Garden Island HSF13.820.220.122.521.323.618.017.016.418.219.521.123.518.922.223.018.221.820.418.717.820.420.420.021.821.019.417.519.617.317.5
Gosnells City15.119.524.020.625.019.015.415.016.821.021.021.223.220.017.116.615.918.718.520.114.017.815.615.3
Jandakot Aero13.119.420.118.518.325.017.014.511.312.718.720.222.723.622.922.917.620.919.416.814.417.015.418.021.518.917.811.313.414.112.7
Karnet10.215.620.120.922.015.411.412.213.815.416.521.720.218.219.216.615.616.718.815.511.913.912.312.7
Mandurah13.319.622.223.021.725.619.617.015.518.019.020.624.825.124.823.822.122.820.618.517.619.819.918.622.121.619.116.418.216.616.1
Millendon (Swan Valley)13.219.419.916.919.926.116.812.111.111.919.120.222.521.720.418.416.918.716.813.313.416.815.316.420.417.118.211.415.012.611.5
Pearce RAAF13.920.420.417.320.827.117.112.410.612.119.821.524.524.118.516.915.717.217.314.414.614.612.915.219.216.917.511.114.314.912.2
Perth Airport13.219.120.017.320.124.217.713.412.213.318.419.924.023.722.921.317.620.018.415.814.317.215.517.821.818.418.612.114.813.912.7
Perth Metro13.619.320.619.419.524.618.416.213.013.818.520.020.721.121.821.619.820.318.917.415.618.316.419.021.518.918.616.116.715.812.9
Rottnest Island14.919.121.320.921.322.618.517.017.118.819.721.722.423.422.721.520.821.719.517.818.519.420.619.521.720.519.618.218.617.617.7
Swanbourne14.119.822.621.821.925.618.216.114.716.720.021.125.322.623.222.820.421.520.117.916.519.018.318.922.119.818.516.218.716.114.0
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 December 2019
12345678910111213141516171819202122232425262728293031
Anketell - - - - - - - 1.4 - - - - - - - - - - - 3.1 - - - - - - - - - - -
Araluen - - - - - - 0.8 - - - - - - - - - - - 5.6











Bickley - - - - - - - 0.8 - - - 0.2 - - - - - - - 7.0 - - - - - - - - - - -
Bungendore - - - - - - - 3.2 0.2 - - - - - - - - - - 6.8 - - - - - - - - - 0.2 -
Chidlow - - - - - - - - 0.6 - - - - - - - - - - 1.8 - - - - - - - - - - -
Garden Island HSF - - - - - - - 0.4 - - - - - - - - - - 0.2 0.8 - - - - - - - - - - -
Gidgegannup - - - - - - - - - - - - - - - - - - - 4.2 - - - - - - - - - - -
Gosnells City - - - - - - - 1.0 - - - -
- - - - - - - - - - - - - - - - - -
Huntly - - - - - - - 0.2 - - - - - - - - - - - 9.8 - - - - - - - - - -
Jandakot Aero - - - - - - - 0.6 - -
- - - - - - 0.2 - 3.0 - - - - - - - - - - -
Jarrahdale - - - - - - - 3.6 - - - - - - - - - - - 7.2 - - - - - - - - - 0.2 -
Karnet - - - - - - 0.4 - - - - -

- - - - - 7.6 - - - - - - 0.2 -
Karragullen North - - - - - - - - - - - - - - - - - - - 7.6 - - - - - - - 0.4
Maida Vale - - - - - - - 2.0 - - - - - - - - - - - 3.4 - - - - - - - - - - -
Mandurah - - - - - - - - - - - - - - - - - - - 0.4 - - - - - - - - - - -
Millendon (Swan Valley) - - - - - - -
- - - - - - - - - - - 2.8 - - - - - - - - - - -
Mount Solus - - - - - - - 1.8 - - - - - - - - - - - 4.0 0.2 - - - - - - - - - -
Muchea - - - - - - - 0.4 - - - - - - - - - - - 1.2 - - - - - - - - - - -
Mundaring - - - - - - - 0.2 - - - - - - - - - - - 5.4 - - - - - - - - - - -
Pearce RAAF - - - - - - - - - - - - -
- - - - - 0.8 - - - - - - - - - - -
Perth Airport - - - - - - - 0.4 - - - - - - - - - - - 1.8 - - - - - - - - - - -
Perth Metro - - - - - - - 0.4 - - - - - - - - - -
1.8 - - - - - - - - - 0.2 -
Pinjarra Refinery - - - - - - - - - - - - - - - - - - 2.2 0.8 - - - - - - - - - - -
Pinjarra South - - - - - - - - - - - - - - - - - - - 1.4 - - - - - - - - - - -
Roleystone - - - - - - - 1.0 - - - - - - - - - - - 7.8










Rottnest Island - - - - - - - 0.8 - - - - - - - - - - - 1.0 - - - - - - - - - - -
Serpentine - - - - - - - 1.8 - - - - - - - - - - - 3.2 - - - - - - - - - - -
Subiaco Treatment Plant - - - - - - - 1.0 - - - - - - - - - - - 1.6 - - - - - - - - - - -
Swanbourne - - - - - - - 1.0 - - - - - - - - - - - 1.6 - - - - - - - - - 0.2 -
Tamala Park (Mindarie) - - - - - - - 0.2 - - - - - - - - - - - 1.2 - - - - - - - - - - -
Werribee - - - - - - - - - - - - - - - - - - - 0.6 - - - - - - - - - - -
Whiteman Park - - - - - - 1.6 - - - - - - - - - - - 2.4 - - - - - - - - - - -
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 10 am on Wednesday 8 January 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