Perth in December 2013: A warm and dry month

  • Rainfall: below average
  • Maximum temperature: very much above average
  • Minimum temperature: near average
  • Rainfall

    Monthly rainfall totals in December 2013 across the Perth metropolitan area were below average, and less than 5 mm. The highest monthly rainfall total in the Perth area was 4.6 mm at Werribee, in the eastern hills, recorded on a single day, the 6th. This was also the highest daily fall in the Perth metropolitan area during the month.

    Only a few rainfall events were reported in Perth in December 2013. The month started with light rainfall on the 1st due to a westerly flow following the passage of a weak cold front at the end of November, with totals across the Perth metropolitan area generally less than 2 mm. A trough near the west coast brought thunderstorms and showers to many sites on the 6th, though daily rainfall totals were less than 3 mm.

    Perth Metro recorded only 1.8 mm on one day (1st) in December 2013, which was below the long term December average of 13.3 mm on 3.9 rain days. It was Perth Metro's driest December for four years, since December 2009 when zero rainfall was recorded.

    Perth has only recorded 12.0 mm of rainfall on two rain days between 21 October and 31 December. This rainfall occurred on the last day of November and first day of December, and although it is not the driest November and December period on record at Perth Metro in terms of rainfall amount (the record is a total of 3.8 mm in November and December 1891), it is the driest in terms of the number of rain days (days when measurable rainfall is recorded). The previous lowest number of rain days in November and December since records commenced at Perth Metro in 1876 was three in 1891, 1909, and 1997.

    Maximum temperature

    Mean maximum temperatures in December 2013 were generally very much above average across Perth. Although being close to normal on the offshore islands, mean maximum temperatures were between 1 ºC to 3 ºC warmer than normal on the coastal plain and in the hills. Mean maxima ranged from the mid-twenties on the offshore islands to the high twenties near the coast and in the hills, and the low thirties across the inland coastal plain.

    Warm to hot days with daily maxima in the thirties and low forties were observed on the coastal plain and in the hills on the 5th and 6th, from the 10th to 16th, the 23rd, and from the 28th to 30th. The hottest day for most sites was the 14th with maximum temperatures in the high thirties and low forties. Pearce RAAF recorded a maximum of 42.6 ºC on both the 14th and 15th, which was the highest temperature of the month in Perth. Cool to mild days with daily maxima in the low to mid-twenties were observed on the first three days of December, the 8th, and the 31st. A maximum of 20.3 ºC at Garden Island on the 3rd was the lowest maximum temperature for the month in Perth.

    From the 12th to 16th, inland sites experienced an unseasonal hot spell. A run of maximum temperatures above 38 ºC at Pearce RAAF was recorded during this period, whilst a run of four consecutive days above 40 ºC (recorded from the 13th to 16th) had not been seen previously in December at Pearce RAAF in an observational record going back to 1940. Temperature readings at Bickley were comparatively lower, but a run of four days with daily maximum temperatures greater than 36 ºC (13th to 16th) was also the longest such hot spell in December at the site in 19 years of record.

    Perth Metro's mean maximum temperature in December 2013 was 30.5 ºC, which was the equal sixth warmest December in 115 years of record, equal with 2011, whilst last year Perth Metro recorded its third warmest December on record. Daily maxima at Perth Metro ranged from a mild of 23.5 ºC on the 3rd to a very hot 40.4 ºC on the 14th. Perth Metro recorded five consecutive days with daily maximum temperatures at or above 36 ºC between the 12th and 16th. This was only the fourth time that five or more consecutive days with daily maximum temperatures at or above 36 ºC had occurred in December at Perth Metro since records commenced in 1897; the other occasions being: five days in Dec 1899, seven days in 1931, and seven days in 2012 (from Christmas Day to New Year's Eve).

    Minimum temperature

    Mean minimum temperatures in December 2013 in Perth were near average at most sites, though were close to 1 ºC above average in the southeastern suburbs and in the hills. Mean minima ranged from the mid-teens in the hills to the mid-to-high teens on the inland coastal plain, to the high teens near the coast and on the islands.

    Nights were mostly mild to warm in December, though cool to cold nights were reported from the 2nd to the 5th, the 23rd and 24th, and the 26th for coastal plain sites. The coolest night was the 4th for most sites, and Medina Research Centre registered the lowest temperature in Perth for the month on this day with a minimum of 8.4 °C. Most sites recorded their warmest night of the month on the 16th and Gosnells City recorded a minimum of 25.0 °C that day, the highest minimum in December 2013 in the Perth metropolitan area.

    Perth Metro's mean daily minimum temperature in December 2013 was 16.7 °C, which is close to the long-term average of 16.4 °C, and the mildest December for three years. Daily minima at Perth Metro during December 2013 ranged from a cool 13.2 °C on the 4th to a warm 20.8 °C on the 16th.

    Sunshine & Phenomena

    Perth recorded an average daily sunshine of 12.1 hours in December 2013, which is above the long-term mean of 11.5 hours per day.

 

Further information

Media
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Extremes in December 2013
Hottest day 42.6 °C at Pearce RAAF on the 14th
42.6 °C at Pearce RAAF on the 15th
Warmest days on average 32.8 °C at Pearce RAAF
Coolest days on average 25.5 °C at Garden Island HSF
29.1 °C at Swanbourne
Coldest day 20.3 °C at Garden Island HSF on the 3rd
21.7 °C at Bickley on the 1st
Coldest night 8.4 °C at Medina Research Centre on the 4th
Coolest nights on average 14.5 °C at Bickley
Warmest nights on average 18.1 °C at Rottnest Island
17.2 °C at Gosnells City
Warmest night 25.0 °C at Gosnells City on the 16th
Wettest overall 4.6 mm at Werribee
Wettest day 4.6 mm at Werribee on the 6th
Highest wind gust 78 km/h at Rottnest Island on the 3rd
78 km/h at Bickley on the 20th




Summary statistics for December 2013
Maximum temperatures
for December
(°C)
Minimum temperatures
for December
(°C)
Rainfall
for December
(millimetres)
Mean for
December
2013
Diff
from
average
Highest for
December
2013
Mean for
December
2013
Diff
from
average
Lowest for
December
2013
Total for
December
2013
Average
for
December
Rank of
December
2013
Fraction of
December
average
Bickley 29.3 +1.3 38.6 14th 14.5 +0.9 9.1 4th 0.8 13.4 low 6%
Champion Lakes 30.2   38.5 14th 17.1   12.8 4th 0.2
Garden Island HSF 25.5 -0.1 31.9 5th 17.6 +0.4 13.9 4th 2.6 12.4 low 21%
Gosnells City 31.9 +1.5 41.2 14th 17.2 +1.0 13.0 2nd 2.4 11.6 low 21%
Jandakot Aero 30.2 +1.2 39.1 14th 14.9 +0.2 9.5 23rd 2.0 10.7 average 19%
Pearce RAAF 32.8 +2.6 42.6 15th 14.8 +0.3 9.3 23rd 0.6 10.6 low 6%
Perth Airport 31.1 +2.2 40.3 14th 15.5 +0.6 9.9 23rd 1.0 11.3 low 9%
Perth Metro 30.5 +1.5 40.4 14th 16.7 +0.3 13.2 4th 1.8 13.3 low 14%
Rottnest Island 25.6 +0.6 31.0 5th 18.1 +0.5 14.0 4th 1.2 8.2 low 15%
Swanbourne 29.1 +1.2 36.6 13th 17.0 +0.5 12.4 4th 0.2 12.3 low 2%

Daily maximum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley21.722.223.325.429.230.725.723.926.529.930.333.336.438.637.937.628.727.427.725.525.428.132.129.630.529.427.231.536.132.724.5
Champion Lakes23.423.224.527.731.131.426.925.128.631.231.834.537.238.537.138.027.928.529.227.127.930.032.229.230.429.428.131.935.632.125.1
Garden Island HSF22.421.820.327.831.929.922.520.623.726.928.929.530.626.729.028.025.622.625.426.825.626.125.822.924.122.223.625.723.825.722.6
Gosnells City25.324.825.528.932.033.328.226.429.832.834.836.540.141.239.040.030.329.730.728.529.531.034.430.529.533.537.233.427.0
Jandakot Aero24.023.523.928.632.031.727.124.828.532.532.635.538.039.137.636.928.027.730.228.627.829.232.827.928.927.628.131.134.930.925.0
Medina Research Centre23.423.022.629.032.733.026.528.432.733.035.635.838.036.436.627.426.429.4
Pearce RAAF26.026.326.028.732.834.529.627.229.933.434.938.240.542.642.641.432.330.831.228.928.830.835.832.733.731.530.134.838.535.527.8
Perth Airport24.824.225.128.132.233.828.025.629.232.533.636.239.140.338.337.729.629.431.628.228.229.533.729.432.028.429.233.235.432.326.5
Perth Metro24.123.623.528.232.032.427.525.128.632.133.536.139.040.437.137.128.427.830.528.228.729.933.929.430.828.228.332.232.631.025.8
Rottnest Island22.922.621.324.031.030.223.522.122.624.827.129.228.529.329.130.125.424.124.725.424.225.327.324.924.323.925.125.224.925.824.4
Swanbourne24.123.823.329.933.332.225.823.928.833.732.134.936.632.231.933.827.626.728.230.429.329.529.526.727.725.627.232.527.828.425.8

This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.
The temperatures in this table are coloured by
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 difference from average


Daily minimum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley13.110.49.99.19.516.715.812.810.911.413.315.716.720.622.119.919.816.514.212.410.211.413.416.914.516.015.512.616.015.616.4
Champion Lakes16.213.713.212.813.820.718.816.014.215.117.019.621.022.619.123.819.518.717.916.114.015.716.616.315.314.517.516.515.919.117.6
Garden Island HSF17.815.715.013.914.118.418.515.614.215.317.620.021.718.221.922.419.119.618.016.414.816.217.417.816.018.619.316.218.119.319.5
Gosnells City16.013.017.513.513.420.518.616.814.015.217.420.321.021.219.025.019.118.517.815.713.915.514.515.617.516.115.417.518.4
Jandakot Aero15.210.811.110.013.318.416.615.813.214.716.918.019.616.415.721.215.818.516.915.413.313.49.511.612.810.616.715.814.316.614.8
Medina Research Centre16.512.013.88.413.321.416.516.013.014.617.019.321.017.616.121.317.019.017.515.1
Pearce RAAF13.09.911.212.213.920.316.616.213.614.618.116.518.314.213.618.114.619.318.015.814.413.79.311.216.010.814.516.413.915.816.3
Perth Airport15.411.110.113.013.418.217.116.514.315.517.116.919.417.015.721.015.619.017.715.913.414.19.911.716.010.818.716.215.018.017.6
Perth Metro16.414.714.213.213.520.018.116.614.215.517.218.320.417.518.920.818.419.017.816.014.315.713.814.215.814.518.816.517.317.919.0
Rottnest Island16.616.815.614.014.620.119.816.014.816.218.519.821.219.220.522.220.619.218.016.815.317.318.919.116.918.419.317.018.920.118.9
Swanbourne16.914.114.212.414.020.118.616.013.415.418.120.121.618.919.421.519.918.917.615.814.215.913.917.114.616.218.916.316.717.919.5

This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.
The temperatures in this table are coloured by
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 difference from average


Daily rainfall
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley 0.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Champion Lakes 0.2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Garden Island HSF 0.4 - - - - 1.2 1.0 - - - - - - - - - - - - - - - - - - - - - - - -
Gosnells City 0.8 - - - - - 1.6 - - - - - - - - - - - - - - - - - - - - - - - -
Jandakot Aero 0.6 - - - - 1.4 - - - - - - - - - - - - - - - - - - - - - - - - -
Jarrahdale 1.4 - - - - - 1.2 - - - - - - - - - - - - - - - - - - 0.2 - - - - -
Medina Research Centre 0.5 - - - - - 0.5 - - - - - - - - - - - - -










Pearce RAAF 0.2 - - - - 0.2 0.2 - - - - - - - - - - - - - - - - - - - - - - - -
Perth Airport 0.6 - - - - 0.4 - - - - - - - - - - - - - - - - - - - - - - - - -
Perth Metro 1.8 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Roleystone 1.0 - - - - - 0.6























Rottnest Island 1.2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Serpentine 0.6 - - - - - 2.6 - - - - - - - - - - - - - - - - - - - - - - - -
Swanbourne - - - - - 0.2 - - - - - - - - - - - - - - - - - - - - - - - - -

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 marked like this 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).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.


Notes

A Monthly Climate Summary is prepared to list the main features of the weather in Perth using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 8 am on Thursday 2 January 2014. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages 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.

The ACORN-SAT dataset is being used for temperature area averages from December 2012 onwards. The major change from earlier datasets is that the ACORN-SAT dataset commences in 1910, rather than 1950, and hence rankings are calculated using a larger set of years.

Further information

Media
(03) 9669 4057
Enquiries