Perth in September 2012: A warm month with mostly near average rainfall

  • Rainfall: near average to above average
  • Maximum temperature: above average
  • Minimum temperature: near average

Rainfall

September 2012 rainfall across the Perth metropolitan area was generally close to average; however, some sites reported above average rainfall. Bickley in the hills reported 207.8 mm for the month, which is very much above average, and the fifth highest September total in 44 years of record at Bickley. Both Bickley and Perth Airport recorded their highest September rainfall totals in over ten years.

A strong cold front moved through the Perth region on the 3rd, bringing moderate to heavy rainfall. Bickley recorded the highest daily total from this event with 67.2 mm in the 24 hours to 9am on the 4th, which is the 4th highest daily total for the site in September in 44 years of record, and was the highest daily total in WA for September 2012. Garden Island observed its highest September daily rainfall total on the 4th with 21.2 mm recorded. Cold fronts and a westerly flow over the southwest of the state during the latter part of the month brought further rainfall to the Perth area, with moderate falls observed in the 24 hours to 9am on the 22nd and 27th.

Perth Metro recorded 90.8 mm of rainfall on 15 rain days in September 2012, which is slightly above average and the first month at Perth Metro to exceed the mean monthly rainfall total since April. Perth Metro's year to date rainfall total remains very much below average, and in combination with the driest July in 137 years of record, and a very much below average May, Perth Metro has recorded its ninth driest January to September period on record with 514.2 mm on 82 rain days. Perth Metro's driest January to September period was in 1914 when 421.4 mm was recorded, whilst in 2010, Perth Metro's second driest year, it recorded its fourth driest January to September period with 454.2 mm.

Maximum temperature

Mean maximum temperatures in September 2012 were above average across the Perth region, with most sites observing mean daily maxima in the low twenties.

Relatively warm spells were recorded across the metropolitan area from the 8th to the 10th, 14th to 17th, and on the 30th, with most sites recording their warmest day for the month on the 9th. The highest temperature recorded in Perth in September was 30.2 °C at Gosnells City on the 9th. Cooler days were reported on the 4th, 6th, and 22nd, whilst the 27th was the coolest day of the month at all recording sites, with the maximum of 10.9 °C at Bickley the lowest in the metropolitan area for September 2012.

Perth Metro's mean daily maximum temperature in September 2012 was 21.5 °C, which is 1.4 °C above average, and equal 6th highest on record. Temperatures ranged from a high of 29.3 °C on the 9th, the warmest September day at Perth Metro in 6 years, to a low of 14.9 °C on the 27th.

For the January to September period, Perth Metro observed a mean maximum temperature of 25.1 °C, which is the second highest mean maximum temperature for the year to September, only behind a mean of 25.3 °C observed in January to September 2011.

Minimum temperature

Mean minimum temperatures in September 2012 were generally close to average across the Perth region, with mean minima generally in the 8 °C to 11 °C range, though 1 to 2 °C higher at Garden Island and Rottnest Island.

Mild overnight temperatures were reported on the 10th and 11th, and 17th to 21st at most sites, with the highest minima for the month recorded on either the 10th or 17th. Gosnells City recorded a minimum of 17.8 °C on the 17th, the highest for the metropolitan area for September 2012. Cool nights were recorded on the 6th and 7th, 12th and 13th, 23rd and 24th, and 28th and 29th. Most recording sites reported their lowest temperature for the month on the 28th, with Jandakot Aerodrome recording the lowest temperature across the Perth region this month with 1.0 °C.

Perth Metro's mean daily minimum temperature in September was 9.8 °C, 0.4 °C above the September average. Minima ranged from a mild 15.6 °C on the 10th, to a cold 3.8 °C on the 28th.

Sunshine

Perth recorded an average daily sunshine of 8.7 hours in September 2012, which is the 6th sunniest September on record and the sunniest since the record of 9.3 hours per day was set in 2010. The average sunshine for September is 7.7 hours per day.

Further information

Media
(03) 9669 4057
Enquiries

Extremes in September 2012
Hottest day 30.2 °C at Gosnells City on the 9th
Warmest days on average 21.8 °C at Gosnells City
Coolest days on average 18.1 °C at Bickley
Coldest day 10.9 °C at Bickley on the 27th
Coldest night 1.0 °C at Jandakot Aero on the 28th
Coolest nights on average 8.2 °C at Bickley
Warmest nights on average 13.1 °C at Rottnest Island
11.1 °C at Swanbourne
Warmest night 17.8 °C at Gosnells City on the 17th
Wettest overall 207.8 mm at Bickley
Wettest day 67.2 mm at Bickley on the 4th
Highest wind gust 107 km/h at Garden Island HSF on the 27th

Record highest September daily rainfall
Highest daily rainfall
in September 2012 (mm)
Previous wettest
for September
Years of
record
Garden Island HSF 21.2 on the 4th 18.6 on the 25th in 2007 11



Highest total September rainfall for at least 10 years
Total rainfall
for September 2012 (mm)
Most recent September
at least this wet
Years since
wetter
Average for
September
Bickley 207.8 209.7 in 1996 16 123.6
Perth Airport 103.6 114.4 in 1998 14 72.2



Summary statistics for September 2012
Maximum temperatures
for September
(°C)
Minimum temperatures
for September
(°C)
Rainfall
for September
(millimetres)
Mean for
September
2012
Diff
from
average
Highest for
September
2012
Mean for
September
2012
Diff
from
average
Lowest for
September
2012
Total for
September
2012
Average
for
September
Rank of
September
2012
Fraction of
September
average
Bickley 18.1 +0.7 25.9 9th 8.2 0.0 3.7 28th 207.8 123.6 high 168%
Champion Lakes 20.4   27.8 9th 10.6   3.6 28th 107.4
Garden Island HSF 19.4 +0.6 27.8 16th 12.4 +0.6 6.7 28th 66.2 60.4 average 110%
Gosnells City 21.8 +1.1 30.2 9th 10.7 +0.7 3.3 28th 105.5 81.7 high 129%
Jandakot Aero 21.1 +1.2 29.1 9th 8.4 +0.3 1.0 28th 114.2 86.2 high 132%
Medina Research Centre 21.2 +1.0 28.9 9th 10.0 +0.9 2.7 29th 69.0 76.3 average 90%
Pearce RAAF 21.5 +1.5 28.7 9th 8.8 +0.1 2.9 24th 74.2 68.8 average 108%
Perth Airport 21.4 +1.3 29.5 9th 8.8 -0.1 1.9 28th 103.6 72.2 high 143%
Perth Metro* 21.5 +1.4 29.3 9th 9.8 +0.4 3.8 28th 90.8 80.8 average 112%
Rottnest Island 19.4 +0.7 24.0 9th 13.1 +0.3 8.9 28th 48.0 52.7 average 91%
Swanbourne 21.4 +1.7 29.2 16th 11.1 +0.2 5.3 28th 90.8 81.0 average 112%

Daily maximum temperature
Central Coast (09)123456789101112131415161718192021222324252627282930
Bickley17.317.615.611.114.515.216.122.225.920.517.517.019.122.223.624.823.716.818.417.618.114.117.418.016.214.810.914.718.424.9
Champion Lakes19.119.319.515.117.417.018.224.527.821.619.418.521.424.226.427.124.319.920.019.620.416.420.218.518.817.814.216.520.027.4
Garden Island HSF19.719.119.016.118.115.819.324.325.421.919.516.818.618.719.227.822.920.220.020.119.015.917.919.019.017.814.415.918.123.9
Gosnells City22.021.620.815.518.417.619.526.030.223.821.320.022.626.027.028.326.521.522.221.421.516.021.220.821.219.115.218.021.029.0
Jandakot Aero20.120.420.215.318.517.319.325.029.123.120.219.221.625.025.828.125.620.621.120.421.617.919.519.320.318.414.916.419.728.1
Medina Research Centre20.121.519.515.819.317.719.226.128.923.920.319.321.224.025.228.626.322.521.820.117.020.220.921.017.515.015.819.427.7
Pearce RAAF20.021.121.116.219.217.719.324.928.723.419.919.421.424.725.627.826.921.622.120.822.918.020.020.220.619.515.117.420.428.1
Perth Airport20.220.920.215.818.518.019.525.429.523.120.619.922.125.226.728.226.021.021.520.522.317.820.219.520.418.915.117.420.828.1
Perth Metro20.520.820.815.918.817.519.525.629.323.220.619.622.025.625.928.625.221.922.621.021.417.720.219.820.519.214.917.120.728.5
Rottnest Island20.219.618.716.118.516.318.823.924.021.519.917.418.220.019.622.222.020.920.620.419.817.017.119.519.418.415.315.518.823.5
Swanbourne21.120.819.915.919.118.820.226.127.623.120.820.622.524.523.729.222.822.021.521.420.818.020.920.120.219.115.318.219.526.8

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)123456789101112131415161718192021222324252627282930
Bickley9.78.38.95.96.75.03.95.910.214.013.26.25.57.37.710.112.113.010.010.610.97.83.97.010.59.76.63.74.77.0
Champion Lakes9.27.710.48.98.76.47.210.513.216.315.28.08.110.612.113.017.315.212.513.413.611.47.06.712.712.99.83.67.09.8
Garden Island HSF15.612.013.710.811.210.79.112.112.317.316.011.19.510.79.913.817.216.015.714.617.011.98.111.215.013.310.76.78.510.4
Gosnells City8.59.510.98.98.25.48.812.012.016.815.37.59.311.810.014.517.815.312.512.913.110.56.012.812.99.93.35.57.5
Jandakot Aero8.54.810.39.37.53.33.810.96.313.813.94.92.25.65.911.416.615.39.714.512.611.32.72.713.712.89.81.01.74.3
Medina Research Centre13.36.510.510.010.74.96.011.012.116.315.87.55.97.95.011.417.116.214.315.911.24.54.014.413.010.03.42.78.2
Pearce RAAF10.05.07.77.78.84.77.312.214.413.413.63.64.69.05.510.817.214.112.89.812.39.23.72.911.611.19.02.93.25.9
Perth Airport8.96.48.48.17.64.16.810.611.511.913.84.83.59.67.310.315.714.811.710.211.811.34.54.711.911.810.21.94.46.5
Perth Metro12.07.310.48.29.55.46.011.28.815.615.57.85.47.77.511.615.015.412.815.013.011.74.75.713.412.410.73.83.96.5
Rottnest Island14.613.914.19.69.612.010.112.516.117.616.512.411.012.613.415.116.916.014.714.316.411.09.512.314.812.410.58.910.512.4
Swanbourne15.09.111.79.09.78.17.711.013.416.616.49.47.49.39.812.816.015.813.414.715.610.96.77.614.912.410.45.35.48.6

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)123456789101112131415161718192021222324252627282930
Bickley 9.8 0.2 0.6 67.2 9.2 10.4 - - - - 0.8 0.4 - - - - - 12.8 2.0 2.4 1.6 27.0 - - 10.0 10.6 35.6 7.2 - -
Champion Lakes 6.6 - - 33.0 3.8 5.6 - - - - 1.4 - - - - - - 9.8 0.6 4.4 2.6 11.2 - - 5.4 3.0 17.0 2.8 0.2 -
Garden Island HSF 0.8 - 4.0 21.2 1.6 1.8 - - - - 0.4 - - - - - - 4.8 - 4.4 - 7.4 - - 3.8 3.2 7.6 5.0 0.2 -
Gosnells City 2.2 - 0.8 36.0 5.2 4.0 - - - - 1.2 0.1 - - - - - 17.6 1.6 3.6 1.2 - 1.0 - 3.8 2.2 21.6 3.4 - -
Jandakot Aero 8.8 - 2.0 35.4 4.8 3.8 - - - - 1.6 - - - - - - 5.4 2.0 4.2 1.6 13.0 - - 9.4 2.6 16.0 3.6 - -
Jarrahdale 9.2 0.4 0.8 45.6 13.8 5.6 0.2 - - - 0.6 0.4 - 0.4 0.2 - - 6.0 0.8 6.4 1.4 27.4 0.4 0.2 5.0 10.0 27.0 6.2 0.2 -
Medina Research Centre 4.8 - 2.6 16.2 4.4 - - - - - - - - - - - - 2.8 0.2 4.0 1.0 8.8 - - 4.8 3.2 10.6 5.6 - -
Mundaring 12.4 0.2
45.0 12.0 4.8 0.2


3.0 0.6




4.8 2.8 3.0 1.0 13.6
5.0 8.8 23.2



Pearce RAAF >> >> 4.2 20.2 6.2 1.4 0.2 - - - 1.8 0.4 - - - - - 2.8 0.6 1.0 0.8 6.4
- 6.8 4.0 15.4 2.0 - -
Perth Airport 0.8
- 31.2 10.0 2.4 - - - - 1.0 - - - - - - 10.0 1.0 4.4 1.2 13.2 - - 7.6 3.0 14.8 3.0 - -
Perth Metro 1.2 - 0.2 28.2 5.0 2.0 - - - - - 0.2 - - - - - 10.8 - 2.6 1.2 11.8 0.2 - 6.0 4.0 12.0 5.4 - -
Roleystone


39.6





1.8





13.0 0.6 5.6 3.6 21.8

5.6 4.6 25.4


Rottnest Island 3.4 0.2 1.4 12.6 2.8 2.8 - - - - - - - - - - - 2.2 - 3.0 - 6.0 0.2 - 2.8 1.2 4.8 4.6 - -
Serpentine 3.8 - 0.8 26.4 11.0 4.0 - - - - 8.4 0.2 - - - - - 3.0 - 4.6 0.2 17.2 - - 3.4 4.2 13.6 3.6 - -
Swanbourne 1.0 - 1.2 41.0 8.2 1.4 - - - - - - - - - - - 5.4 1.4 0.6 0.6 9.6 - - 3.2 2.8 10.2 4.2 - -

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 12 pm on Tuesday 2 October 2012. 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.
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.

*Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Mt Lawley site, the most significant changes of this kind relate to minimum temperature and rain days.

For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Mt Lawley site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

For PDF files of Perth Metro climate statistics for other months, please click here for extremes and here for averages.

Further information

Media
(03) 9669 4057
Enquiries