Perth in 2015: a very warm year with dry winter and spring

All sites in the Perth metropolitan area recorded above average annual mean maximum temperatures for 2015, with Perth Metro recording its equal warmest year on record. Annual mean minimum temperatures were also above average across Perth. 2015 was a dry year in the Perth area as a result of below average rainfall in winter and spring.

  • Mean maximum temperatures above average for all sites; equal highest at Perth Metro with 2011 and 2012
  • Mean minimum temperatures above average for all sites
  • Rainfall below average for most sites, generally by at least 150 mm
  • Highest number of days over 20 °C in June at Perth Metro
  • Ninth-driest winter on record at Perth Metro
  • Earliest occurrence of 32 °C in September at Perth Metro
  • Warmest October on record at most sites, including Perth Metro which broke the previous mean maximum temperature record for October by 1.0 °C

Mean annual maximum temperatures in 2015 ranged from around 23 °C on the islands and in the hills to about 25 °C or 26 °C across much of the coastal plain, and were generally between 1 °C and 2 °C above average. Perth Metro recorded its equal warmest year in 117 years of record, equal with 2011 and 2012. Apart from a relatively cool autumn, most months experienced warmer than normal daytime temperatures, with record warm days observed in June, September and October for most sites.

Mean annual minimum temperatures in 2015 were also above average. They were about 16 °C on the islands, about 14 °C near the coast, and between 12 °C and 13 °C on the coastal plain and in the hills. Apart from cooler than normal nights in autumn, most months saw minimum temperatures that were average or above, with warmest on record nights observed in October at most sites.

Annual rainfall for 2015 were below average for most sites, with totals ranging from about 500 mm on the islands and in the far northeast of the metropolitan area, to between 600 mm and 700 mm on much of the coastal plain, and to about 900 mm in the hills. Monthly rainfall totals were generally at or below average in most months, with only February and December seeing above average rainfall. However, winter was noticeably dry, with Perth Metro observing its ninth-driest winter on record.

Notable events in 2015

  • 5 January: the hottest day in 2015 across the Perth area with daily maximum temperatures in the low to mid-forties. A temperature of 44.4 °C at Perth Metro was the third-highest January temperature in its 119 years of record
  • 29 January: a deep trough near the west coast triggered widespread thunderstorms in Perth. Hail up to 3 cm in diameter was reported in the suburb of Thornlie, and approximately three thousand homes lost power
  • 1-3 February: Perth Airport recorded thunderstorms on 3 consecutive days, equalling the highest number of consecutive thunderstorm days on record on 17-19 February 1978
  • 7-13 April: The Perth area saw seven consecutive rain days due to a slow moving low pressure system and persistent cloudbands, which was the longest wet spell in April at Perth Metro for 35 years
  • May: Perth Metro only reported 4 rain days, equalling the lowest number of rain days on record (May 2009)
  • June: Perth Metro recorded 21 days with daily maximum temperatures above 20 °C, equalling the highest number of such days on record (June 1983)
  • 9 September: Perth Metro recorded a maximum temperature of 32.1 °C, which is the earliest occurrence of 32 °C in September at Perth Metro, overtaking the previous early-season record (32.3 °C on 18 September 1988)
  • October: unprecedented warmth across the Perth area. The mean maximum temperature of 26.8 °C at Perth Metro was 1.0 °C higher than the previous record in October 1969. Daily maximum temperatures were above 30 °C for 8 days at Perth Metro, exceeding the previous record of 6 days in October 2008

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Extremes in 2015
Hottest day 45.4 °C at Pearce RAAF on 5 Jan
Warmest days on average 26.8 °C at Pearce RAAF
Coolest days on average 22.7 °C at Rottnest Island
23.3 °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 11.8 °C at Bickley
Warmest nights on average 16.0 °C at Rottnest Island
14.3 °C at Swanbourne
Warmest night 27.5 °C at Gosnells City on 28 Jan
Warmest on average overall 19.7 °C at Pearce RAAF
Coolest on average overall 17.5 °C at Bickley
Wettest overall 892.2 mm at Karnet
Driest overall 410.4 mm at Werribee
Wettest day 70.6 mm at Bungendore on 20 Jul
Strongest wind gust 111 km/h at Rottnest Island on 2 Feb
111 km/h at Rottnest Island on 16 May


Record highest annual mean daily maximum temperature
New record
(°C)
Old
record
Years of
record
Annual
average
Pearce RAAF 26.8 26.5 in 2013 51 25.2
Perth Metro 25.7 = 25.7 in 2011, 2012 117* 24.7
*Highest for current or previous Perth sites


Summary statistics for 2015
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean
for
2015
Diff
from
average
Highest
for
2015
Mean
for
2015
Diff
from
average
Lowest
for
2015
Total
for
2015
Average
annual
total
Rank
of
2015
Fraction
of annual
average
Bickley 23.3 +0.7 41.3 5 Jan 11.8 +0.6 2.4 9 Jul 877.8 1076.6 low 82%
Garden Island HSF 23.0 +0.2 39.4 5 Jan 15.3 +0.3 5.0 22 Aug 476.0 598.0 low 80%
Jandakot Aero 25.4 +0.8 43.7 5 Jan 12.0 +0.6 -1.5 9 Jul 651.2 824.3 v low 79%
Karnet 23.5 +0.9 41.0 5 Jan     -0.5 9 Aug 892.2 1162.0 v low 77%
Pearce RAAF 26.8 +1.6 45.4 5 Jan 12.5 +0.3 0.2 9 Jul 500.6 651.1 low 77%
Perth Airport 26.0 +1.5 44.2 5 Jan 13.0 +0.9 0.1 9 Jul 577.8 767.4 v low 75%
Perth Metro 25.7 +1.0 44.4 5 Jan 13.3 +0.5 0.8 9 Jul 617.8 846.6 low 73%
Rottnest Island 22.7 +0.5 39.4 5 Jan 16.0 +0.3 7.3 9 Aug 542.6 691.7 average 78%
Swanbourne 25.0 +0.9 43.2 5 Jan 14.3 +0.4 3.7 9 Jul 667.0 721.2 low 92%
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 Annual 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 9 am on Wednesday 6 January 2016. 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
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