Perth in winter 2015: Dry and mild

Winter rainfall was below average for most sites, and the ninth driest winter at the Perth official site since records commenced in 1876. Days were mostly mild with a few very cold nights. Mean maximum and minimum temperatures were both above average.

  • Ninth driest winter on record at Perth Metro
  • Warmest or equal warmest winter days on record at Pearce and Jandakot
  • Warmest winter nights for nineteen years at Perth Metro

Rainfall in winter 2015 was generally 20% to 30% below the long-term average for most sites in the Perth metropolitan area, with totals ranging from 250 mm–360 mm on the coastal plain and offshore islands, to 400 mm–500 mm in the hills. Perth Metro recorded a total of 315.8 mm on 44 rain days, which was its driest winter since 2012, and ninth driest winter in 139 years of rainfall recordings at the Perth official site.

Mean maximum temperatures in winter 2015 were above average across Perth, and Pearce RAAF and Jandakot Aerodrome experienced their warmest winter on record. For a number of sites, 15 August was the warmest winter day on record as the result of the Perth area being under the influence of northerly winds. Perth Metro recorded a maximum of 27.0 °C on the 15th, its equal ninth highest winter temperature since records commenced in 1897. Perth Metro's lowest maximum temperature in winter 2015 was 15.0 °C on the 8 July, which continued a run of maximum temperatures at or above 15 °C for 25 months, since August 2013. This exceeded the previous longest such run of 24 months without a maximum temperature below 15 °C recorded between July 1987 and June 1989.

Mean minimum temperatures in winter 2015 were also above average across the Perth metropolitan area. Perth Metro recorded a mean minimum of 9.3 °C in winter 2015, which was the warmest winter in terms of overnight temperatures for nineteen years, since winter 1996 when a mean minimum of 9.7 °C was recorded. Bickley recorded its equal warmest winter night on record on 20 June in northwesterly winds ahead of a cut-off low passing the southwest corner of the State, and recorded its equal highest winter mean minimum temperature in 21 years of record.

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Extremes in winter 2015
Hottest day 28.0 °C at Medina Research Centre on 15 Aug
28.0 °C at Swanbourne on 15 Aug
Warmest days on average 20.0 °C at Swanbourne
Coolest days on average 16.3 °C at Bickley
Coldest day 10.9 °C at Bickley on 8 Aug
Coldest night -1.5 °C at Jandakot Aero on 9 Jul
Coolest nights on average 7.8 °C at Karnet
Warmest nights on average 13.2 °C at Rottnest Island
10.7 °C at Swanbourne
Warmest night 17.7 °C at Garden Island HSF on 20 Jun
17.1 °C at Swanbourne on 20 Jun
Warmest on average overall 15.9 °C at Rottnest Island
15.4 °C at Swanbourne
Coolest on average overall 12.3 °C at Karnet
Wettest overall 491.8 mm at Karnet
Wettest day 70.6 mm at Bungendore on 20 Jul
Strongest wind gust 96 km/h at Rottnest Island on 21 Jun

 

Record highest winter temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Medina Research Centre 28.0 on 15 Aug 26.2 on 17 Aug 2014 30 18.9
Rottnest Island 25.3 on 15 Aug 24.9 on 3 Jun 1984 105 18.1
Jandakot Aero 27.0 on 15 Aug = 27.0 on 26 Aug 1998 26 18.5
Swanbourne 28.0 on 15 Aug 26.2 on 6 Aug 2014 22 18.9



Record highest winter mean daily maximum temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Pearce RAAF 19.8 19.7 in 2006 54 18.4
Jandakot Aero 19.5 = 19.5 in 2014 24 18.5



Record highest winter daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Bickley 15.0 on 20 Jun = 15.0 on 7 Aug 2006 22 7.6



Record highest winter mean daily minimum temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Bickley 8.4 = 8.4 in 2007 21 7.6



Record highest winter mean temperature
New record
(°C)
Old
record
Years of
record
Average for
winter
Bickley 12.4 = 12.4 in 2014 21 11.7
Swanbourne 15.4 = 15.4 in 2014 21 14.5

Highest winter mean temperature for at least 20 years
Observed
(°C)
Most recent
higher
Average for
winter
Perth Airport 14.6 14.8 in 1983 13.4



Summary statistics for winter 2015
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean for
winter
2015
Diff
from
average
Highest for
winter
2015
Mean for
winter
2015
Diff
from
average
Lowest for
winter
2015
Total for
winter
2015
Average
for
winter
Rank of
winter
2015
Fraction of
winter
average
Bickley 16.3 +0.6 23.8 15 Aug 8.4 +0.8 2.4 9 Jul 414.8 586.4 v low 71%
Garden Island HSF 18.9 +0.5 25.9 15 Aug 12.1 +0.6 5.0 22 Aug 256.4 315.5 low 81%
Jandakot Aero 19.5 +1.0 27.0 15 Aug 8.0 +0.9 -1.5 9 Jul 351.6 456.0 low 77%
Karnet 16.8 +0.9 25.0 15 Aug 7.8 +1.2 -0.5 9 Aug 491.8 614.5 low 80%
Medina Research Centre 19.8 +0.9 28.0 15 Aug 9.2 +0.7 0.4 9 Jul        
Pearce RAAF 19.8 +1.4 26.8 15 Aug 9.0 +0.4 0.2 9 Jul 255.8 369.2 low 69%
Perth Airport 19.7 +1.2 27.4 15 Aug 9.4 +1.1 0.1 9 Jul 296.4 431.5 v low 69%
Perth Metro 19.7 +0.7 27.0 15 Aug 9.3 +1.2 0.8 9 Jul 315.8 393.8 low 80%
Rottnest Island 18.7 +0.6 25.3 15 Aug 13.2 +0.5 7.3 9 Aug 297.2 395.4 low 75%
Swanbourne 20.0 +1.1 28.0 15 Aug 10.7 +0.6 3.7 9 Jul 327.8 387.1 low 85%
Note: Observations for “Perth Metro” are taken from the current site at Mount Lawley (Bureau number 009225).
Comparisons are made against combined data from the current site (which opened in early 1993) and the previous site at Perth Regional Office (009034),which ran from 1876 to early 1992.
Observations for “Rottnest Island” are taken from the current site at Rottnest Island (Bureau number 009193).
Comparisons are made against combined data from the current site(which opened in 1995) and the previous site at Rottnest Island Lighthouse (009038),which ran from 1879 to 1994.

Notes

The Seasonal climate summary lists 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.

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 Tuesday 1 September 2015. 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.

Observations for “Perth Metro” are taken from the current site at Mount Lawley (Bureau number 009225).
Comparisons are made against combined data from the current site (which opened in early 1993) and the previous site at Perth Regional Office (009034), which ran from 1876 to early 1992.

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