Greater Perth in December 2020: very warm with a scorching Christmas Day

December 2020 was very warm across Greater Perth, and it was the second-warmest December on record at the Perth Metro site. Mean maximum temperatures were well above average, with a mild start to the month and a hot spell to Christmas Day. Mean minimum temperatures were also above average.

Below average rainfall

  • Rainfall was below average across Greater Perth, and monthly totals were mostly less than 5 mm although December is typically dry.
  • A number of weak cold fronts produced light rainfall on the 1st,13th and 14th.

Well above average daytime temperatures

  • Mean maximum temperatures were 1–3 °C above average across Greater Perth; mean minimum temperatures were 0.5–2 °C above average for most sites.
  • Perth Metro recorded a mean maximum temperature of 31.7 °C, which was its second-warmest December on record, behind 2019.
  • It was the equal second-warmest December on record at Perth Airport with a mean maximum temperature of 32.4 °C, equal with 1999 and behind 2019.
  • The first December morning was the coldest of the month, with minimum temperatures generally below 10 °C; Perth Metro recorded a minimum of 6.6 °C on the 1st, its lowest December temperature on record.
  • Perth Metro (along with several other sites) recorded 3 consecutive days with temperatures of 40 °C leading to a scorching Christmas Day, which was its second hot spell in December, and the first was between 13 and 15 December in 2019.
  • Perth Metro recorded a maximum temperature of 40.4 °C on the 25th, which was its hottest Christmas Day for 13 years when a maximum of 40.7 °C was recorded on 25 December 2007.

Perth Metro

  • Total rainfall for Perth Metro was 4.4 mm, which is 42% of the long-term average of 10.4 mm
  • The mean daily maximum temperature for Perth Metro was 31.7 °C, which is 2.4 °C above the long-term average of 29.3 °C
  • The warmest day was 41.1 °C on the 24th, and the coolest day was on the 13th when the temperature reached 23.1 °C
  • The mean daily minimum temperature for Perth Metro was 16.9 °C, which is 0.5 °C above the long-term average of 16.4 °C
  • The coldest morning was 6.6 °C on the 1st, and the warmest morning was on the 30th when the minimum temperature was 24.1 °C

Further information

Media
(03) 9669 4057

Extremes in December 2020
Hottest day 42.6 °C at Pearce RAAF on the 24th
Warmest days on average 33.4 °C at Pearce RAAF
Coolest days on average 26.5 °C at Rottenest Island
Coldest day 19.6 °C at Karney on the 13th
Coldest night 4.8 °C at Karney on the 1st
Coolest nights on average 14.3 °C at Buckley
14.3 °C at Karnet
Warmest nights on average 17.9 °C at Rottnest Island
Warmest night 26.2 °C at Gosnells City on the 30th
26.2 °C at Pearce RAAF on the 30th
Warmest on average overall 25.0 °C at Pearce RAAF
Coolest on average overall 22.2 °C at Bickley
22.2 °C at Rottnest Island
Wettest overall 10.6 mm at Bickley
Driest overall 0.2 mm at Garden Island HSF
Wettest day 6.4 mm at Bickley on the 13th
Strongest wind gust 80 km/h at Rottnest Island on the 26th


Record lowest December temperature
New record
(°C)
Old
record
Years of
record
Average for
December
Gosnells City 8.0 on the 1st = 8.0 on the 2nd in 2002 29 16.4
Perth Metro 6.6 on the 1st 7.9 on the 7th in 2007 27 16.4



Summary statistics for December 2020
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
December
2020
Diff
from
average
Highest for
December
2020
Mean for
December
2020
Diff
from
average
Lowest for
December
2020
Total for
December
2020
Average
for
December
Rank of
December
2020
Fraction of
December
average
Bickley 30.0 +1.8 39.1 25th 14.3 +0.5 6.5 1st 10.6 14.5 average 73%
Garden Island HSF 27.7 +2.2 38.7 24th 17.8 +0.5 11.2 1st 0.2 9.9 lowest 2%
Gosnells City 32.6 +2.1 40.5 23rd 17.3 +0.9 8.0 1st 7.4 11.3 average 65%
Jandakot Aero 31.6 +2.4 41.2 24th 16.2 +1.4 5.0 1st 2.2 10.4 average 21%
Karnet 30.0 +1.8 38.6 25th 14.3 +0.8 4.8 1st 4.8 18.6 low 26%
Millendon (Swan Valley) 32.8   42.2 24th 16.3   6.2 1st 2.0
Pearce RAAF 33.4 +2.9 42.6 24th 16.7 +2.1 5.4 1st
Perth Airport 32.4 +3.3 41.7 24th 16.4 +1.4 4.9 1st 4.0 11.1 average 36%
Perth Metro 31.7 +2.4 41.1 24th 16.9 +0.5 6.6 1st 4.4 10.4 average 42%
Rottnest Island 26.5 +1.4 37.7 23rd 17.9 +0.2 12.8 1st 1.4 10.5 low 13%
Swanbourne 29.1 +1.2 39.7 23rd 17.6 +1.0 9.0 1st 2.8 10.9 average 26%

Daily maximum temperatures for December 2020
12345678910111213141516171819202122232425262728293031
Bickley21.826.230.021.323.425.530.137.232.533.329.030.719.822.026.628.728.230.032.130.530.233.937.638.939.132.926.430.936.334.231.1
Garden Island HSF19.720.421.622.619.724.129.134.730.730.834.326.323.121.625.424.126.827.228.723.828.730.537.538.726.223.630.031.235.732.628.2
Gosnells City24.628.531.025.227.533.539.537.132.333.123.724.530.430.631.532.635.034.033.837.040.540.235.729.734.039.634.633.2
Jandakot Aero22.926.328.523.723.425.132.739.434.737.633.132.323.123.429.829.231.231.333.532.332.935.539.741.239.231.129.733.639.033.631.7
Karnet25.329.420.422.725.429.836.130.533.629.230.119.623.326.428.528.529.631.529.230.134.237.238.638.632.125.630.335.635.231.9
Mandurah21.224.525.423.721.823.529.836.732.435.034.528.222.631.333.138.637.436.028.229.131.737.034.028.6
Millendon (Swan Valley)25.329.431.924.925.127.533.240.335.836.531.833.624.325.129.831.031.132.935.233.033.337.240.842.241.732.929.133.939.336.333.1
Pearce RAAF25.130.132.824.425.428.333.540.835.636.532.234.124.725.530.431.431.634.035.834.334.137.341.342.642.534.430.134.240.337.433.4
Perth Airport23.928.330.323.624.826.633.040.135.736.732.332.722.924.830.031.031.232.335.333.233.337.240.541.740.931.729.434.039.534.732.4
Perth Metro23.528.823.923.425.033.139.433.136.333.132.723.123.529.029.330.331.234.331.132.936.140.241.140.429.629.734.139.033.630.8
Rottnest Island20.121.623.022.921.021.427.932.130.730.333.326.122.221.324.023.825.125.125.424.225.827.237.735.826.324.226.027.734.729.026.0
Swanbourne21.823.523.922.921.722.630.638.231.136.733.727.723.022.927.426.028.429.331.826.531.334.139.739.329.825.829.732.837.926.926.6
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 2020
12345678910111213141516171819202122232425262728293031
Bickley6.59.511.711.49.79.911.714.318.619.620.318.714.39.610.111.512.312.414.414.512.212.414.822.024.119.012.310.316.021.418.7
Garden Island HSF11.212.315.517.515.613.915.718.419.521.122.820.217.714.414.315.416.516.618.817.815.817.720.620.522.220.215.714.621.224.921.7
Gosnells City8.012.513.314.012.515.618.124.023.520.517.815.014.015.415.616.219.517.516.016.919.124.316.114.319.026.222.0
Jandakot Aero5.09.610.814.112.010.915.117.217.221.423.717.617.111.913.614.615.815.818.117.115.316.318.919.917.320.315.413.919.625.421.5
Karnet4.811.711.911.110.112.214.916.418.221.118.114.410.19.812.112.612.214.914.712.112.816.122.819.817.112.210.817.520.916.7
Mandurah10.213.214.516.315.713.815.418.619.421.524.421.517.314.317.420.124.023.819.515.314.620.924.821.4
Millendon (Swan Valley)6.28.29.714.49.69.914.118.817.023.023.917.717.411.411.815.316.316.517.917.915.616.819.622.316.422.515.914.020.725.120.9
Pearce RAAF5.48.79.315.110.610.214.220.417.223.422.418.017.311.613.514.916.216.619.116.116.017.321.223.316.222.316.214.721.526.221.1
Perth Airport4.99.512.114.210.012.514.118.117.422.423.717.017.312.713.915.216.016.516.817.915.616.218.822.117.222.215.614.019.925.021.0
Perth Metro6.69.812.115.414.412.815.418.017.921.123.119.417.413.414.015.216.516.418.518.015.716.519.220.519.222.016.014.219.024.121.5
Rottnest Island12.814.116.016.815.914.616.219.618.519.822.520.116.615.514.715.716.917.219.217.916.318.220.723.721.019.716.015.019.923.320.9
Swanbourne9.012.113.116.615.012.915.919.919.120.823.820.916.913.714.215.516.217.119.117.415.917.320.223.919.321.516.014.820.924.221.8
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 2020
12345678910111213141516171819202122232425262728293031
Anketell 1.1 - - - - - - - 0.2 - - - 0.9 1.0 - - - - - - - - - - - - - - - - -
Bickley 2.2
- - - - - - - - - - 6.4 2.0 - - - - - - - - - - - - - - - - -
Bungendore 2.0 - - - - - - - - - - - 2.6 0.8 - - - - - - - - - - - - - - - - -
Chidlow - - - - - - - - - - - - 2.8
















Garden Island HSF - - - - - - - - - - - - - 0.2 - - - - - - - - - - - - - - - - -
Gidgegannup 0.2 - - - - - - - - - - - 3.6 0.6 - - - - - - - - - - - - - - - - -
Gosnells City 0.2 - - - - - - - - - - - 1.2 6.0 - - - - - - - - - - - - - - - - -
Huntly 2.2 - - - - - - - - - - - 2.4 0.8 - - - - - - - - - - - - - - - - -
Jandakot Aero - - - - - - - - - - - - 1.2 0.8 - - - - - - - - 0.2 - - - - - - - -
Jarrahdale 1.0 - - - 0.2 - - - - - - - 2.4 0.4 0.2 - - - - - - - - - - - - - - - -
Karnet 1.6 - - - - - - - - - - - 1.0 2.2 - - - - - - - - - - - - - - - - -
Karragullen North 1.8 - - - - - - - - - - - 4.4 2.2
















Maida Vale 0.6 - - - - - - - - - - - - 1.0
















Mandurah 1.0 - - - - - - - - - - - 0.4 0.2







- - - - - - - - -
Millendon (Swan Valley) 0.2 - - - - - - - - - - - 1.4 0.4 - - - - - - - - - - - - - - - - -
Mount Solus 1.2 - - - - - - - - - - - 1.8 2.0 0.2 - - - - - - - - - - - - - - - -
Muchea 0.2 - - - - - - - - - - - 2.0 - - - - - - - - - - - - - - - - - -
Mundaring 0.6 - - - - - - - - - - - 5.8 2.8
















Perth Airport - - - - - - - - - - - - 3.0 1.0 - - - - - - - - - - - - - - - - -
Perth Metro 0.4 -
- - - - - - - - - 3.8 0.2 - - - - - - - - - - - - - - - - -
Pinjarra South 0.4 - - - - - - - - - - - 0.2 1.8 - - - - - - - - - - - - - - - - -
Roleystone - - - - - - - - - - - - 4.4

















Rottnest Island 0.4 - - - - - - - - - - - 1.0 - - - - - - - - - - - - - - - - - -
Serpentine 0.8 - - - - - - - - - - - 0.8 - - - - - - - - - - - - - - - - - -
Swanbourne 1.2 - - - - - - - - - - - 1.4 0.2 - - - - - - - - - - - - - - - - -
Tamala Park (Mindarie) - - - - - - - - - - - - 2.4 - - - - -












Wanneroo 0.2 - - - - - - - - - - 6.6
















Werribee 0.4 - - - - - - - - 0.2 - - 0.6 - - - - - - - - - - - - - - - - - -
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 8 am on Monday 4 January 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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