Perth in August 2013: above average rainfall with very mild days & nights

  • Rainfall: above average
  • Maximum temperature: above average
  • Minimum temperature: warmest August on record for a number of sites

Rainfall

Rainfall across the Perth metropolitan area during August 2013 was generally above average, with only Rottnest Island recording a below average August total rainfall. In contrast the coastal site of Swanbourne recorded its wettest August in 20 years of record. Monthly rainfall totals ranged from near 90 mm on Rottnest Island to 140 mm to 190 mm on the coastal plain, and almost 300 mm in the hills.

A weak cold front brushed through the southwest corner of WA on the 1st, bringing generally light showers to the Perth metropolitan area. A slow moving cloudband and northwesterly winds over southern WA ahead of an approaching cold front between the 5th and 8th brought persistent showery conditions to much of the Southwest Land Division, with moderate to heavy falls in the Perth metropolitan area. Bickley recorded a daily total of 80.2 mm on the 8th, which was the second wettest day in August at Bickley in its 36 years of record, and the wettest day for any month at Bickley in over 12 years, since 137.0 mm was recorded on 30 July 2001. Mainly light rainfall continued across the Perth area between the 9th and 18th under a persistent westerly airstream with embedded weak cold fronts, although a cold front on the 15th brought moderate rainfall to most sites. Consecutive rain days occurred on the last six days of the month as a complex low pressure system and upper level trough moved through southern WA on the 25th and 26th bringing some moderate falls, followed by a second low pressure system on the 27th and 28th bringing moderate to heavy falls, and a cold front on the 31st bringing some moderate falls.

Perth Metro recorded 167.4 mm of rainfall on 22 rain days during August 2013, which is above the long-term average of 133.1 mm, and the wettest August at Perth Metro in nine years since 175.6 mm was recorded in 2004. The highest daily rainfall at Perth Metro in August 2013 was 45.4 mm on the 8th, which was its wettest August day for 10 years, since 45.8 mm was recorded on 11 August 2003. Perth Metro recorded 15 consecutive rain days between 5 and 19 August, and 22 in total for the month, the wettest August in terms of rain days for 15 years, since 22 rain days were recorded in August 1998. Last August (2012), Perth Metro recorded 87.2 mm on 16 rain days.

Maximum temperature

Mean maximum temperatures in August 2013 were above average across the Perth metropolitan area and a number of sites recorded their warmest or equal warmest August on record. Mean maxima ranged from the mid-teens in the hills to the low twenties on the coastal plain.

A run of mild days was reported for the first 7 days of the month with daily maximum temperatures generally over 20 ºC. Cool days were observed on the 8th,11th,13th, and 15th to 17th, with coastal and offshore sites recording their coolest day of the month on the 16th. Mild days returned on the 19th, and were also reported from the 22nd to 25th, with most observing sites in the Perth metropolitan area recording their warmest day of the month on the 24th, including Gosnells City, which recorded a maximum of 26.9 ºC, the warmest day of the month for the metropolitan area. A cool to cold day was observed on the 27th as the result of cloudy wet conditions and Bickley recorded a maximum of 12.6 ºC, the lowest maximum temperature in Perth for August 2013.

Perth Metro's mean maximum temperature in August 2013 was 20.4 °C, which was the warmest August for Perth Metro in 116 years of record.  The previous record was 20.3 °C in August 1902 (111 years ago). Daily maxima ranged from a cool of 16.8 °C on the 27th to a warm 26.4 °C on the 24th.

Minimum temperature

Mean minimum temperatures in August 2013 were very much above average across the Perth area, with a number of sites being the warmest on record. Mean minima were in the 9 ºC to 12 °C range on the coastal plain and in the hills, and in the 13 ºC to 14 ºC range on the offshore islands.

Most nights in August 2013 were cool to mild across the Perth area, including the 1st, between the 5th and 13th, the 15th, 17th, 25th and 26th, and 30th and 31st. The mildest nights were the 7th and 8th, with all sites recording their highest minimum for the month on these days, and a number of sites recording their highest or equal highest August minimum temperature on record. The highest minimum temperature in the Perth metropolitan area during August 2013 was 17.3 ºC both at Rottnest Island and Swanbourne on the 7th. Relatively cold nights were reported on the 4th, 14th, 16th, 20th, and 22nd to 24th, with most sites recording their lowest temperatures of the month on the 16th or 20th, though the lowest minimum temperature in the Perth area in August was 3.3 °C at Jandakot Aerodrome on the 24th.

Perth Metro's mean daily minimum temperature in August 2013 was 10.6 °C, which was well above the average of 8.1 °C, and the warmest August for 15 years since a mean of 10.8 °C was recorded in 1998. During August 2013, Perth Metro recorded no cold nights (a cold night in Perth is when the minimum temperature is 5 °C or less). This was the first time in August that the Perth Metro site at Mount Lawley had not recorded a cold night since records commenced in 1994. Daily minima ranged from a cold 5.7 °C on the 20th to a record high 17.1 °C on the 7th.

Sunshine & Phenomena

Perth recorded an average daily sunshine of 6.7 hours in August 2013, which was slightly below the long-term average of 7.2 hours.

A suspected waterspout crossed the Perth metropolitan coast near North Coogee on the 6th, causing injury to 6 people (two serious) when scaffolding on a building site collapsed. Buildings were damaged and a heavy concrete building slab was lifted up.

Further information

Media
(03) 9669 4057
Enquiries

Extremes in August 2013
Hottest day 26.9 °C at Gosnells City on the 24th
Warmest days on average 20.8 °C at Gosnells City
Coolest days on average 16.9 °C at Bickley
Coldest day 12.6 °C at Bickley on the 27th
Coldest night 3.3 °C at Jandakot Aero on the 24th
Coolest nights on average 9.4 °C at Pearce RAAF
Warmest nights on average 14.0 °C at Rottnest Island
12.2 °C at Swanbourne
Warmest night 17.3 °C at Rottnest Island on the 7th
17.3 °C at Swanbourne on the 7th
Wettest overall 297.4 mm at Bickley
Wettest day 80.2 mm at Bickley on the 8th
Highest wind gust 87 km/h at Rottnest Island on the 15th
81 km/h at Perth Airport on the 15th
81 km/h at Bickley on the 31st

Record highest total August rainfall
Total rainfall
for August 2013 (mm)
Previous wettest
for August
Years of
record
Average for
August
Swanbourne 164.2 144.8 in 2001 20 115.5



Record highest August mean daily maximum temperature
Mean daily maximum
temperature
for August 2013 (°C)
Previous warmest
for August
Years of
record
Average for
August
Pearce RAAF 20.2 = 20.2 in 2006 52 18.3
Rottnest Island 19.4 19.2 in 2006 115 17.8
Gosnells City 20.8 = 20.8 in 2011 20 19.3
Perth Metro 20.4 20.2 in 2011 116 18.9
Swanbourne 20.2 20.0 in 2011 19 18.7



Record highest August daily minimum temperature
Highest daily minimum
temperature
in August 2013 (°C)
Previous warmest
for August
Years of
record
Average for
August
Pearce RAAF 16.3 on the 7th 16.2 on the 23rd in 1966 54 8.1
Medina Research Centre 16.6 on the 8th 16.3 on the 12th in 1987 28 8.0
Jandakot Aero 16.5 on the 7th = 16.5 on the 7th in 2006 24 6.9
Perth Metro 17.1 on the 7th 17.0 on the 7th in 2006 116 8.0
Swanbourne 17.3 on the 7th = 17.3 on the 7th in 2006 20 9.9
Garden Island HSF 17.2 on the 8th 16.3 on the 31st in 2006 12 11.0



Record highest August mean daily minimum temperature
Mean daily minimum
temperature
for August 2013 (°C)
Previous warmest
for August
Years of
record
Average for
August
Medina Research Centre 10.7 10.3 in 1983 27 8.0
Jandakot Aero 9.9 9.6 in 1998 23 6.9
Bickley 9.5 8.9 in 2006 19 7.5
Swanbourne 12.2 11.8 in 1998 19 9.9
Garden Island HSF 13.1 12.6 in 2006 11 11.0


Summary statistics for August 2013
Maximum temperatures
for August
(°C)
Minimum temperatures
for August
(°C)
Rainfall
for August
(millimetres)
Mean for
August
2013
Diff
from
average
Highest for
August
2013
Mean for
August
2013
Diff
from
average
Lowest for
August
2013
Total for
August
2013
Average
for
August
Rank of
August
2013
Fraction of
August
average
Bickley 16.9 +1.0 23.1 24th 9.5 +2.0 4.6 16th 297.4 172.4 v high 173%
Champion Lakes 19.2   24.4 24th 11.4   6.3 16th 173.6
Garden Island HSF 19.2 +1.2 21.9 23rd 13.1 +2.1 7.9 28th 125.2 91.3 high 137%
Gosnells City 20.8 +1.5 26.9 24th         156.1 126.2 high 124%
Jandakot Aero 19.8 +1.2 25.0 24th 9.9 +3.0 3.3 24th 194.6 126.4 v high 154%
Medina Research Centre         10.7 +2.7 5.1 20th        
Pearce RAAF 20.2 +1.9 26.2 24th 9.4 +1.3 4.6 16th 140.7 104.5 high 135%
Perth Airport 20.3 +1.8 26.1 24th 9.9 +1.9 3.9 20th 151.0 117.8 high 128%
Perth Metro 20.4 +1.5 26.4 24th 10.7 +2.6 5.7 20th 167.4 133.1 high 131%
Rottnest Island 19.4 +1.6 22.9 23rd 14.0 +1.7 10.1 16th 94.0 99.3 average 95%
Swanbourne 20.2 +1.5 23.7 24th 12.2 +2.3 8.0 23rd 164.2 115.5 highest 142%

Daily maximum temperature
Central Coast (09) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Bickley 17.6 17.7 19.2 19.7 18.2 17.8 18.0 14.7 16.9 15.7 15.8 15.3 16.2 16.2 14.3 14.1 14.8 16.6 16.9 16.7 17.7 18.6 20.9 23.1 16.5 15.4 12.6 15.4 16.7 16.6 17.4
Champion Lakes 19.5 19.2 21.6 21.1 20.9 21.0 21.4 17.3 19.1 17.8 17.5 18.3 18.1 17.9 17.0 16.0 17.3 20.3 19.5 18.3 18.4 21.6 23.4 24.4 20.4 18.1 15.2 17.7 18.5 19.4 20.4
Garden Island HSF 19.4 19.4 19.8 21.8 21.2 20.4 21.4 18.2 19.2 18.8 17.7 18.5 18.4 18.5 18.3 16.7 18.4 17.7 19.4 18.5 17.3 20.4 21.9 20.8 20.4 17.9 17.9 18.1 19.1 19.5 20.2
Gosnells City 20.8 21.5 22.4 22.8 22.2 21.8 21.8 17.6 20.9 19.4 19.0 19.3 19.7 17.5 18.2 18.6 19.1 21.7 19.7 19.8 22.4 25.3 26.9 21.8 19.0 19.1 22.0 21.6
Jandakot Aero 20.5 19.9 21.1 22.3 21.9 21.8 21.9 18.1 19.9 18.2 18.0 18.7 18.5 18.6 17.8 16.7 18.5 18.9 20.1 19.1 19.2 21.4 23.9 25.0 21.1 18.1 15.8 18.6 19.5 20.0 21.2
Pearce RAAF 20.3 20.5 21.9 23.0 22.6 23.0 23.2 18.3 20.4 20.0 18.3 18.9 18.4 19.4 18.5 16.9 18.0 19.0 20.6 19.4 20.0 20.5 23.9 26.2 19.5 18.9 17.3 18.6 19.8 20.9 20.9
Perth Airport 20.9 20.6 21.4 22.7 22.2 21.8 22.1 17.8 19.4 19.4 18.6 19.9 19.0 20.2 18.6 16.9 18.8 18.7 21.1 19.4 20.2 22.2 24.5 26.1 20.4 18.2 16.4 18.7 20.3 20.1 21.3
Perth Metro 21.0 21.0 21.7 22.8 22.5 22.1 21.9 17.7 20.1 19.8 18.7 20.5 18.9 19.7 19.4 16.9 19.0 19.0 20.6 19.6 19.8 22.0 24.7 26.4 20.7 18.5 16.8 19.4 20.0 20.2 21.1
Rottnest Island 20.1 19.6 19.8 22.4 21.5 21.6 22.0 17.7 19.5 19.1 18.1 19.2 18.4 18.9 17.4 17.2 18.4 19.1 20.0 18.8 17.6 18.6 22.9 20.9 19.7 18.5 17.2 19.0 19.3 19.8 20.6
Swanbourne 20.7 20.6 20.5 22.3 22.4 21.6 20.8 17.9 20.0 20.1 18.8 19.9 18.5 19.5 18.4 17.1 19.0 19.2 21.4 19.3 20.5 21.9 23.6 23.7 20.9 18.7 17.1 19.8 19.5 20.1 21.0

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
Bickley10.58.57.810.213.313.414.113.710.210.210.49.111.45.910.04.68.78.16.77.58.38.26.99.112.011.06.57.28.610.712.5
Champion Lakes12.89.011.99.014.615.316.216.010.712.612.511.314.29.012.06.310.510.210.77.410.49.39.09.813.212.410.09.410.612.914.8
Garden Island HSF15.011.914.39.815.915.316.317.214.614.414.414.015.111.313.611.413.412.011.39.812.112.79.59.914.615.112.37.911.914.315.9
Gosnells City12.77.910.58.315.416.515.910.311.911.810.46.511.29.510.76.110.08.47.68.912.09.011.014.5
Jandakot Aero11.56.611.25.012.915.016.516.312.411.012.011.214.15.611.95.512.68.16.83.58.15.64.33.311.211.17.87.310.013.215.5
Medina Research Centre13.88.911.46.415.115.816.613.412.313.113.314.57.913.66.79.010.58.85.15.47.05.79.413.012.710.48.6
Pearce RAAF10.16.95.27.012.215.116.315.810.88.111.510.411.46.510.34.610.78.17.74.96.85.45.95.611.013.27.59.67.111.814.4
Perth Airport12.17.47.87.013.214.916.615.79.710.69.99.414.07.711.75.410.28.510.03.97.85.57.16.510.412.48.68.38.711.314.9
Perth Metro11.28.89.06.813.615.517.116.311.810.813.012.615.17.913.06.311.27.89.45.79.47.05.96.411.714.38.58.49.113.415.1
Rottnest Island15.414.014.614.915.815.517.316.014.014.514.414.414.912.813.510.112.712.712.712.713.313.712.914.814.314.413.010.813.214.115.7
Swanbourne15.111.010.310.415.915.417.316.614.313.914.514.314.69.312.79.412.19.69.69.110.89.08.010.012.414.49.29.310.014.214.8

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 rainfall
Central Coast (09) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Bickley 1.6 0.4 0.2 0.2 7.0 19.4 8.8 80.2 27.2 3.4 12.2 1.0 2.4 12.4 2.6 22.0 3.0 0.4 - 0.2 0.2 - 0.2 - - 25.4 1.6 32.8 0.8 6.4 25.4
Champion Lakes 2.8 0.8 - - 2.6 12.8 0.4 47.6 7.2 2.4 8.2 1.0 3.6 3.6 2.0 12.6 2.6 0.4 - 0.2 - - - - - 4.6 1.2 37.8 1.4 8.6 9.2
Garden Island HSF 0.2 2.6 - 0.2 0.6 18.2 12.4 15.4 1.4 7.0 10.2 1.0 4.2 0.8 4.4 5.6 0.2 0.2 - - 0.4 - - - 0.2 4.0 2.6 22.8 1.8 5.2 3.6
Gosnells City - - »» »» 3.0 16.2 1.0 37.7 9.7 1.9 9.1 »» 2.4 6.7 2.4 13.4 1.8 0.4 - - - - - - - 13.6 »» 23.8 2.8
10.2
Jandakot Aero 0.2 0.2 - - 4.2 11.0 2.0 51.0 7.2 1.8 8.6 0.8 4.2 3.2 5.8 15.8 1.2 0.2 - - - - - - - 7.6 2.8 49.2 1.2 11.4 5.0
Jarrahdale 4.2 0.8 - 0.2 0.6 42.2 12.0 48.2 5.0 9.8 20.4 0.2 4.8 2.6 10.2 18.8 5.6 - 0.2 0.2 0.8 0.2 0.2 0.2 - 4.6 1.6 24.0 5.0 22.2 8.8
Pearce RAAF 8.4 0.4 - - 5.8 11.0 2.2 33.8 »» »» 8.2 0.4 0.4 5.9 - 12.2 4.8 1.6 - - - - - - - 11.2 1.0 19.2 0.2 1.8 12.2
Perth Airport 1.0 - - - 4.6 14.4 2.6 32.0 11.6 2.8 3.8 0.4 0.6 8.8 1.0 16.6 4.2 0.8 - - - - - - - 6.4 1.8 23.4 0.2 5.8 8.2
Perth Metro 3.8 - - - 0.8 11.2 4.6 45.4 13.4 0.8 2.8 0.4 1.0 3.4 2.0 16.0 6.8 1.8 0.4 - - - - - - 9.4 3.4 27.0 0.4 5.2 7.4
Roleystone 3.4 0.2 - - 4.0 18.6 1.2 60.2 9.0 5.2 7.0 1.4 6.6 6.4 6.0 17.2 3.8 - 0.2 - 0.4









Rottnest Island 3.0 - - - 0.8 14.6 1.0 20.2 3.0 0.2 0.8 0.2 0.6 1.2 1.8 5.8 1.0 0.2 - - 1.8 - - - 2.0 4.6 4.0 22.0 0.6 3.6 1.0
Serpentine 4.8 2.2 - - 4.4 16.0 8.6 30.0 2.8 7.4 15.6 0.2 3.0 2.2 7.0 14.2 4.0 - - - 1.6 - - - - 3.8 0.8 16.8 2.2 16.8 6.2
Swanbourne 6.4 0.2 - 0.2 1.2 11.6 1.6 36.0 10.0 2.4 0.6 0.2 2.8 5.0 1.2 10.8 6.2 4.4 - 0.2 - - - - 0.4 8.0 3.2 34.6 1.8 7.0 8.2

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 10 am on Monday 2 September 2013. 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