Perth in September 2014: warm temperatures with near average rainfall

Rainfall in the Perth area was near average for most sites during September 2014. After a very dry start to the month, a number of rainfall events during the middle and latter parts returned rainfall totals to near average. Monthly rainfall totals ranged from about 50 mm to 80 mm on the islands and coastal plain, to over 140 mm in the hills. Rain days were mostly below average with only 10 to 12 rain days recorded for the month for most sites.

Across the Perth metropolitan area, mean daily maximum temperatures were 1 °C to 2 °C above the long-term average, and a number of sites broke their highest mean maximum temperature for September. Perth Metro recorded a mean maximum temperature of 22.0 °C which is the highest mean maximum temperature at the current Mount Lawley site (temperature record commenced in 1994). For the composite Perth Metro site, it was the second warmest September in 115 years of record, behind the 22.6 °C in September 1987. Most days in September in Perth were mild with daily maxima commonly in twenties on the coastal plain. The 20th was the warmest day in September with all sites breaking their previous highest September temperature on record. The coolest day for most locations was observed on the 22nd or 23rd in the wake of a cold front.

Mean minimum temperatures were generally 1 °C above average across the Perth region, with a few sites observing their warmest September on record. Most nights were mild with minima in teens and the warmest night for most locations was the 21st after a very warm day on the 20th. Cool to cold nights with minima below 10 °C were reported across many locations on the 1st, 12th, 14th, and from 22nd to 25th for coastal plain sites, and the coldest night was the 14th when Jandakot recorded a minimum of 3.1 °C. Perth Metro recorded a mean minimum temperature of 11.4 °C, which is the second highest mean minimum temperature at the current Mount Lawley site, behind the 11.6 °C observed last September.

  • Two strong cold fronts produced widespread, although mainly minor, damage over southern WA on the 7th to 9th. Given the path of damage, a tornado likely moved through Forrestfield (southeast of Perth). Severe wind gusts in excess of 90 km/h were observed at a number sites, while coastal sites Rottnest Island and Ocean Reef observed gusts in excess of 100 km/h. An apartment block in Attadale lost its roof.
  • A deep trough off the west coast on the 20th resulting all Perth Metropolitan sites recording their highest September temperature on record, with temperatures reaching the mid-thirties.
  • A strong cold front and associated cloudband produced significant rainfall with daily falls of 20 mm to 40 mm across Perth on the 21st.
  • A strong cold front and associated cloudband produced moderate rainfall across Perth during the event on the 27th.

Further information

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Extremes in September 2014
Hottest day 34.8 °C at Gosnells City on the 20th
Warmest days on average 22.9 °C at Gosnells City
Coolest days on average 19.0 °C at Bickley
Coldest day 13.1 °C at Bickley on the 8th
Coldest night 3.1 °C at Jandakot Aero on the 14th
Coolest nights on average 9.6 °C at Bickley
Warmest nights on average 14.1 °C at Rottnest Island
12.3 °C at Swanbourne
Warmest night 18.2 °C at Rottnest Island on the 21st
17.7 °C at Gosnells City on the 21st
Warmest on average overall 17.2 °C at Gosnells City
Coolest on average overall 14.3 °C at Bickley
Wettest overall 141.0 mm at Bickley
Driest overall 53.6 mm at Rottnest Island
65.4 mm at Pearce RAAF
Wettest day 40.6 mm at Armadale on the 22nd
Strongest wind gust 102 km/h at Rottnest Island on the 7th



Record highest September temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Perth Metro 34.2 on the 20th 32.7 on the 30th in 1918 115 20.2
Perth Airport 34.5 on the 20th 31.6 on the 26th in 1961 71 20.1
Pearce RAAF 33.0 on the 20th 31.4 on the 29th in 2006 57 20.0
Medina Research Centre 34.0 on the 20th 30.9 on the 18th in 1988 30 20.3
Jandakot Aero 34.2 on the 20th 30.4 on the 20th in 1994 25 20.0
Rottnest Island 30.8 on the 20th 27.0 on the 28th in 1990 49 18.8
Gosnells City 34.8 on the 20th 31.3 on the 29th in 2006 22 20.7
Swanbourne 34.2 on the 20th 29.8 on the 29th in 2010 22 19.8
Bickley 30.5 on the 20th 29.0 on the 29th in 2006 21 17.4



Record highest September mean daily maximum temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Pearce RAAF 22.0 = 22.0 in 1987 53 20.0
Gosnells City 22.9 22.4 in 2010 21 20.7
Swanbourne 21.9 21.5 in 2010 21 19.8

Highest September mean daily maximum temperature for at least 20 years
Observed
(°C)
Most recent
higher
Years since
higher
Average for
September
Rottnest Island 20.1 20.2 in 1990* 23 18.8

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




Record highest September mean daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Rottnest Island 14.1 13.9 in 2013 116 12.9
Gosnells City 11.6 11.5 in 2013 21 10.1
Bickley 9.6 = 9.6 in 2013 20 8.2



Record highest September mean temperature
New record
(°C)
Old
record
Years of
record
Average for
September
Perth Airport 16.3 15.8 in 1994 70 14.5
Pearce RAAF 16.1 15.8 in 1994 53 14.4
Jandakot Aero 15.9 15.4 in 1990 24 14.1
Rottnest Island 17.1 16.9 in 1931 115 15.8
Gosnells City 17.2 16.7 in 1994 21 15.4
Swanbourne 17.1 16.3 in 2013 21 15.4
Bickley 14.3 14.0 in 1994 20 12.8



Summary statistics for September 2014
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
September
2014
Diff
from
average
Highest for
September
2014
Mean for
September
2014
Diff
from
average
Lowest for
September
2014
Total for
September
2014
Average
for
September
Rank of
September
2014
Fraction of
September
average
Bickley 19.0 +1.6 30.5 20th 9.6 +1.4 5.4 1st 141.0 127.7 average 110%
Garden Island HSF 20.2 +1.4 32.9 20th 13.4 +1.4 9.6 1st 71.4 68.3 average 105%
Gosnells City 22.9 +2.2 34.8 20th 11.6 +1.5 6.0 1st 82.6 83.3 average 99%
Jandakot Aero 21.8 +1.8 34.2 20th 10.0 +1.8 3.1 14th 72.0 88.0 average 82%
Pearce RAAF 22.0 +2.0 33.0 20th 10.2 +1.4 3.5 14th 65.4 70.3 average 93%
Perth Airport 22.1 +2.0 34.5 20th 10.6 +1.7 4.2 14th 69.8 73.6 average 95%
Perth Metro 22.0 +1.8 34.2 20th 11.4 +1.9 5.8 14th 77.0 81.3 average 95%
Rottnest Island 20.1 +1.3 30.8 20th 14.1 +1.2 9.6 22nd 53.6 59.7 average 90%
Swanbourne 21.9 +2.1 34.2 20th 12.3 +1.3 7.6 1st 74.8 84.5 low 89%

Daily maximum temperatures for September 2014
123456789101112131415161718192021222324252627282930
Bickley15.818.317.315.922.818.714.513.115.917.318.521.119.319.520.421.625.522.823.430.519.215.413.419.620.719.914.316.418.321.0
Garden Island HSF19.320.019.820.623.221.718.817.919.219.920.320.817.619.918.621.719.619.622.232.920.216.016.420.120.521.817.719.419.721.4
Gosnells City19.922.021.520.727.322.919.417.820.321.022.424.522.823.124.225.026.225.826.834.823.018.517.423.023.523.523.320.822.024.5
Jandakot Aero19.420.721.120.825.322.818.918.020.220.520.822.820.822.222.124.325.924.124.534.222.318.116.621.221.823.317.119.820.822.8
Medina Research Centre20.320.820.221.425.823.019.818.419.520.422.222.821.722.022.624.725.622.624.034.021.817.718.222.0
Pearce RAAF18.520.519.619.325.622.718.818.719.621.621.224.221.521.723.324.026.624.724.833.023.118.717.123.123.323.017.520.321.223.5
Perth Airport18.820.820.119.325.622.918.917.719.721.221.523.521.822.823.724.627.025.025.234.522.218.717.022.122.223.118.019.921.023.8
Perth Metro18.921.120.319.625.722.918.917.619.921.421.623.721.222.122.824.626.224.024.634.221.918.117.121.622.523.018.220.321.623.4
Rottnest Island18.719.818.519.322.221.819.217.620.020.720.121.118.119.419.020.720.921.021.830.818.516.316.220.120.921.717.419.720.420.0
Swanbourne20.021.420.320.925.122.219.018.021.322.322.422.120.021.923.326.025.122.323.134.221.218.018.121.122.222.618.321.121.922.8
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 September 2014
123456789101112131415161718192021222324252627282930
Bickley5.49.610.16.411.013.611.17.59.411.69.39.29.27.610.18.29.311.311.111.214.56.75.97.19.19.913.110.511.48.9
Garden Island HSF9.613.413.810.714.117.114.812.114.116.212.610.713.711.212.912.313.415.313.214.718.09.710.812.212.116.614.514.115.114.4
Gosnells City6.012.711.011.014.016.014.710.013.014.59.88.511.16.810.012.412.811.414.317.79.57.58.59.712.015.113.213.210.0
Jandakot Aero5.211.310.79.514.114.413.710.412.515.37.86.49.23.17.111.511.69.27.68.415.68.53.95.86.39.415.713.611.310.6
Medina Research Centre6.711.911.19.913.915.814.611.412.815.510.36.59.85.09.011.89.39.28.712.016.08.95.87.76.9
Pearce RAAF9.612.711.010.713.913.011.811.512.213.39.66.18.73.56.811.911.07.28.511.216.710.45.65.75.69.314.411.012.09.9
Perth Airport7.112.811.59.413.714.214.311.512.513.89.06.98.44.27.611.812.58.39.010.716.49.54.77.68.611.114.213.512.410.3
Perth Metro7.212.712.39.413.814.715.011.813.114.59.77.911.05.810.311.912.011.210.913.015.99.46.56.88.311.715.413.912.612.2
Rottnest Island11.313.315.011.514.217.715.111.513.915.813.810.613.912.914.613.215.016.916.416.418.29.612.413.214.513.114.413.414.615.1
Swanbourne7.613.312.69.414.516.315.311.713.315.812.110.211.18.711.611.611.312.013.614.116.28.38.49.110.612.915.513.614.713.5
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 September 2014
123456789101112131415161718192021222324252627282930
Bickley - - - - - 3.0 17.2 28.2 24.0 0.2 0.4 0.2 0.2 - - - - - - - 32.2 - 0.2 - - 11.0 21.0 3.0 0.2
Garden Island HSF - - - - - 1.8 4.6 6.2 2.0 - 1.0 - 1.4 - - - - - - - - 38.0 - - - - 9.4 3.0 3.8 0.2
Gosnells City - 0.1 - - - 1.4 8.4 10.2 9.0 - - - - - - - - - - - - 29.0 - - - - 4.0
Jandakot Aero - - - - - 0.8 9.0 10.0 2.6 0.4 - - 0.4 - - - - - - - - 28.8 - - - - 6.6 10.8 2.4 0.2
Jarrahdale 0.2 - - 0.2 - 1.4 19.0 11.0 6.0 0.8 0.6 0.6 - - 0.2 - - 0.2 0.2 - 0.2 33.6 0.2 0.2 0.2 - 27.6 20.4 5.6 1.2
Medina Research Centre - 0.2 0.1 - - 1.0 4.0 8.0 3.8 - 0.5 - 0.8 - - - - - - - - 25.0 - - -




Mundaring - - 0.2 - - 3.0 13.2 24.0 10.2 0.6 0.8 0.2 - - 0.1 - - - - - - 31.2 - 0.2 - - - 29.8 4.0 0.6
Pearce RAAF - - 0.4 - 0.2 3.2 7.6 11.6 6.2 - - - 0.2 - - - - - - - - 22.6 -
- - 0.2 10.0 1.8 1.4
Perth Airport - - - - - 3.2 7.2 12.4 4.8 0.2 - - 0.2 - - - - - - - - 20.8 - - - - 10.2 6.2 2.8 1.8
Perth Metro - - - - - 1.6 6.6 8.0 3.0 0.2 2.2 - 0.4 - - - - - - - - 35.8 - - - - 11.4 3.8 3.4 0.6
Roleystone - - - - - - 19.4 13.4 11.4 6.0 1.4 - - - - - - - - - - 34.0







Rottnest Island - - - - - 3.8 2.0 3.0 0.8 - 3.2 - 2.0 - - - - - - - - 30.4 - - - - 5.0 1.0 2.4 -
Serpentine - - - - - 1.4 7.0 20.4 7.0 0.4 1.0 0.2 0.2 - - - - - - - - 32.2 - - - - 16.0 9.2 9.4 -
Swanbourne - - - -
1.2 6.6 9.8 1.8 - 2.2 0.2 1.4 - - - - - - - - 37.0 - - - - 9.2 4.0 0.8 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

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.

A Climate Summary is generally published on the first working day of each month.

This statement has been prepared based on information available at 10 am on Wednesday 1 October 2014. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

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.

The ACORN-SAT dataset is used for temperature area averages.

Further information

Media
(03) 9669 4057
Enquiries