Perth in spring 2013: Record warm month

  • Rainfall: above average
  • Maximum temperature: very much above average; 2nd warmest on record at Perth Metro
  • Minimum temperature: above to very much above average; warmest on record for most sites
  • Mean temperature: warmest on record for most sites

Rainfall

Spring 2013 saw above average rainfall in the Perth metropolitan area as the result of a very wet September, despite a near average October and a dry November. Spring rainfall totals were generally in the 140 mm to 220 mm range on the offshore islands and Swan coastal plain, and up to 370 mm in the hills.

Significant rainfall events during spring 2013 in Perth:

  • a cold front and associated cloudband moved through western parts of WA on 3 and 4 September bringing moderate rainfall to much of Perth.
  • a deep trough near the west coast produced showers and thunderstorms in the Perth area on 7 September, with moderate to heavy falls in the northern suburbs and in the hills.
  • frequent strong cold frontsfrom 10 to 27 September brought persistent rainfall and occasional strong winds and thunderstorms across this period, with rainfall reported on most days, and heavy falls reported on the 11th and 12th, 14th, 17th, and 22nd and 23rd.
  • a trough and associated cloudband developed off the west coast and moved across the Perth region on 9 October, resulting in showers with moderate falls for most sites.
  • an extensive cloudband moved across western WA on 19 and 20 October and brought moderate falls to most Perth sites.
  • little significant rainfall was reported for most of November, with the only widespread rainfall occurring on the 29th as a cold front moved through the Perth region.

Perth Metro recorded 192.4 mm of rainfall on 30 rain days during spring 2013, which was above the average of 155.3 mm on 31.4 rain days. Rainfall totals at Perth Metro for the individual months in spring 2013 were: September, 144.2 mm (average 80.9 mm); October, 38.0 mm (average 52.0 mm); and November, 10.2 mm (average 22.4 mm).

Perth Metro registered 40 rainless days between 21 October to 29 November before a weak cold front moved through the region to bring an end to the dry spell. This is the longest spring dry spell at Perth Metro since rainfall records commenced 1876, with the previous longest being 39 rainless days from 16 October to 23 November 1994.

Mean temperature

Mean temperatures (average of daily maximum and minimum temperatures) for spring 2013 were in the high teens across the Perth metropolitan area, and were well above average with a number of sites recording their warmest spring on record. The record warm spring was largely due to record warm nights in September and very much above average days and nights in November.

Perth Metro's mean temperature for spring 2013 was 18.8 C, which is the warmest spring (in terms of average maximum and minimum temperature) on record. The previous record at Perth Metro was 18.7 C in 1982.

Maximum temperature

Daytime temperatures for spring 2013 were very much above average across Perth as a result of a near average September and October, and a very much above average November. Mean daily maxima for spring were in the low twenties in the hills and offshore islands,and in the mid-twenties on the coastal plain.

During spring 2013, sites on the Swan coastal plain experienced seven to fifteen hot days (maximum temperatures 32 C or higher) concentrated in late October and November, whilst sites in the hills and on offshore islands recorded fewer. In contrast, Bickley in the hills experienced six cold days (maximum temperatures 15 C or lower), all in September, whilst no other Perth observation site recorded a maximum below 15 C during spring 2013. The highest temperature in spring 2013 in Perth was 38.8 C at Pearce RAAF on 16 November, and the lowest maximum temperature was 13.2 C at Bickley on 17 September.

Perth Metro's mean daily maximum temperature for spring 2013 was 24.4 C, which was well above the average of 23.2 C, and the second warmest spring for Perth Metro in 116 years of record. Perth Metro's warmest spring was in 2010, with a mean maximum temperature of 25.3 C, whilst last spring (2012) ranked third warmest on record with a mean maximum of 24.1C. Daily maxima at Perth Metro during spring ranged from a cool 17.0 C on 14 September to a very hot 37.2 C on both 30 October and 10 November.

Minimum temperature

Mean daily minimum temperatures during spring 2013 were very much above average with most sites recording their warmest spring on record, whilst Perth Aiport recorded its warmest spring in 50 years. Mean daily minima were generally between 10 C and 14 C in the hills and on the inland coastal plain, grading to 15 C on the offshore islands. Spring 2013 mean minimum temperatures were the result ofa record warm September, a near average October, and a very warm November.

During spring 2013, most sites experienced at least two warm nights with daily minima over 20 C, all occurring in November, while cold nights with daily minima below 9 C ranged from about four nights in the western suburbs to about 18 nights in the eastern suburbs and about 25 in the hills. The highest minimum temperature in spring in Perth was 22.9 C at Pearce RAAF on 16 November and the lowest temperature was 3.1 C at Jandakot Aerodrome on 1 October.

Perth Metro's mean daily minimum temperature for spring 2013 was 13.2 C, well above the spring average of 11.7 C, and the warmest since records commenced at the current Mt Lawley observation site in 1994.Daily minima at Perth Metro ranged from a cold 5.3 C on 6 September to a warm 20.3 C on both 22 and 28 November. Perth Metro recorded no temperature below 5 C in spring 2013; this was the first time this has occurred in spring for 13 years, since 2000.

Wind and Sunshine

Severe wind gusts were recorded on the offshore islands, coastal sites, and hills on the 22nd and 23rd September when two strong cold fronts moved through southwest WA, with Rottnest Island recording the highest wind gust in the metropolitan area for spring 2013 of 107 km/h from the WNW at 0233 WST on the 22nd.

Perths mean daily sunshine was 9.2 hours in spring 2013, which is near the long term average of 9.3 hours per day.

Further information

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Extremes in spring 2013
Hottest day 38.8 C at Pearce RAAF on 16 Nov
Warmest days on average 25.2 C at Pearce RAAF
Coolest days on average 21.8 C at Bickley
Coldest day 13.2 C at Bickley on 17 Sep
Coldest night 3.1 C at Jandakot Aero on 1 Oct
Coolest nights on average 10.9 C at Bickley
Warmest nights on average 15.2 C at Rottnest Island
13.9 C at Swanbourne
Warmest night 22.9 C at Pearce RAAF on 16 Nov
Wettest overall 365.6 mm at Bickley
Wettest day 42.6 mm at Perth Airport on 7 Sep
Highest wind gust 107 km/h at Rottnest Island on 22 Sep

Record highest total spring rainfall

Total rainfall
for spring 2013 (mm)
Previous wettest
for spring
Years of
record
Average for
spring
Garden Island HSF 189.4 174.0 in 2005 12 122.6

Highest total spring rainfall for at least 10 years

Total rainfall
for spring 2013 (mm)
Most recent spring
at least this wet
Years since
wetter
Average for
spring
Jarrahdale 348.6 351.9 in 1973* 35 241.5
Roleystone 311.4 320.0 in 1991 22 214.1
Serpentine 232.0 295.1 in 1973* 19 173.1
Perth Airport 210.8 231.4 in 1996 17 144.4
Swanbourne 204.6 251.8 in 1996 17 152.7
Jandakot Aero 223.0 260.8 in 1999 14 166.6
Medina Research Centre 181.6 203.9 in 1999 14 150.3
Pearce RAAF 192.7 193.8 in 1999 14 129.9

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




Record highest spring mean daily minimum temperature

Mean daily minimum
temperature
for spring 2013 (C)
Previous warmest
for spring
Years of
record
Average for
spring
Pearce RAAF 12.2 11.8 in 1982 52 10.4
Jandakot Aero 12.1 11.3 in 1989 23 10.0
Rottnest Island 15.2 15.1 in 2006 117 14.2
Swanbourne 13.9 13.5 in 2006 20 12.6
Bickley 10.9 10.6 in 2011 19 9.8
Perth Metro 13.2 12.5 in 2006 19 11.7
Garden Island HSF 14.9 14.5 in 2006 11 13.6

Highest spring mean daily minimum temperature for at least 10 years

Mean daily minimum
temperature
for spring 2013 (C)
Most recent spring
at least this warm
Years since
warmer
Average for
spring
Perth Airport 12.4 12.5 in 1963 50 10.6



Record highest spring mean temperature

Mean daily
temperature
for spring 2013 (C)
Previous warmest
for spring
Years of
record
Average for
spring
Perth Airport 18.5 18.3 in 2010 69 16.7
Pearce RAAF 18.7 18.2 in 1994 52 17.0
Jandakot Aero 18.1 17.7 in 2010 23 16.5
Rottnest Island 18.6 = 18.6 in 2010 117 17.4
Swanbourne 18.9 18.7 in 2010 20 17.5
Perth Metro 18.8 18.7 in 1982 116 17.5
Garden Island HSF 18.5 18.3 in 2006 11 17.4



Summary statistics for spring 2013

Maximum temperatures
for spring
(C)
Minimum temperatures
for spring
(C)
Rainfall
for spring
(millimetres)
Mean for
spring
2013
Diff
from
average
Highest for
spring
2013
Mean for
spring
2013
Diff
from
average
Lowest for
spring
2013
Total for
spring
2013
Average
for
spring
Rank of
spring
2013
Fraction of
spring
average
Bickley 21.8 +0.7 35.1 30 Oct 10.9 +1.1 4.5 21 Oct 365.6 235.8 v high 155%
Champion Lakes 23.5 36.2 30 Oct 13.5 6.2 1 Oct 212.4


Garden Island HSF 22.1 +1.0 36.0 10 Nov 14.9 +1.3 8.7 1 Oct 189.4 122.6 highest 154%
Gosnells City 25.2 +1.1 38.2 30 Oct 5.5 1 Oct 198.2 158.0 high 125%
Jandakot Aero 24.0 +1.1 37.0 10 Nov 12.1 +2.1 3.1 1 Oct 223.0 166.6 high 134%
Pearce RAAF 25.2 +1.7 38.8 16 Nov 12.2 +1.8 4.7 1 Oct 192.7 129.9 v high 148%
Perth Airport 24.6 +1.7 37.2 16 Nov 12.4 +1.8 4.0 1 Oct 210.8 144.4 v high 146%
Perth Metro 24.4 +1.1 37.2 10 Nov 13.2 +1.5 5.3 6 Sep 192.4 155.3 high 124%
Rottnest Island 22.0 +1.3 35.7 10 Nov 15.2 +1.0 10.3 21 Oct 144.6 113.5 high 127%
Swanbourne 23.9 +1.5 37.2 10 Nov 13.9 +1.3 7.4 1 Oct 204.6 152.7 high 134%

Notes

A Seasonal 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 2 pm on Sunday 1 December 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