Perth in 2010: One of the hottest and driest years on record

  • One of the driest years on record across the Perth metropolitan area.
  • One of the hottest years on record in terms of mean maximum temperature.
  • Near average mean daily minimum temperature.
  • Sunniest year on record.

Rainfall

2010 was one of the driest years on record across the Perth Metropolitan area. Lowest annual rainfall records were broken at a number of sites due to a culmination of a record dry summer, a record dry winter and below average rainfall in spring. Annual rainfall totals were generally 40 to 50 % lower than normal and in the 350-600 mm range. Mundaring in the Perth hills registered 599.6 mm in 2010 which was the driest year in 107 years of record, and the first annual rainfall total of below 600 mm. The previous lowest annual rainfall record at Mundaring was 653.4 mm in 1914.

Perth Metro recorded 503.8 mm on 65 rain days in 2010, which was the second driest year on record since records commenced in 1876, behind the 466.8 mm in 2006. The 65 rain days was the lowest number of rain days recorded in a year at Perth Metro, the previous record being 88 rain days in 1969. March (total 40.4 mm; average 19.4 mm) and December (total 17.4 mm; average 12.8 mm) were the only two months in 2010 where Perth Metro received rainfall above the monthly average. The wettest day for Perth Metro in 2010 was 9 July when 40.6 mm was recorded, which was the wettest July day since 88.8 mm was recorded on the 30 July 2001.

Extended dry spells, which began in late spring (21 November 2009), were observed at many stations in the Perth area over summer 2009-10, and into March 2010. Perth Airport registered 122 continuous days without measurable rain from 21 November 2009 to 22 March 2010, breaking the previous longest dry spell of 83 days between 24 December 1947 and 15 March 1948. Perth Metro observed 78 days without measurable rainfall from 21 November 2009 to 7 February 2010, when 0.2 mm was recorded, which was Perth Metro's second longest dry spell on record. The longest dry spell at Perth Metro was 83 days between 15 December 1974 and 7 March 1975.

Severe storms swept through the Perth metropolitan area on the afternoon of 22 March, bringing the first significant rainfall to Perth since 19 November 2009. The storm was considered to be one of the worst in Perth's history with damage estimated at over $1 billion, caused mainly by large hail (up to 6 cm) and flash flooding. The highest daily rainfall total recorded in Perth during the event (and for autumn) was 66.8 mm at Wanneroo (DAFWA), whilst Jarrahdale recorded 57.2 mm. For more details of the severe thunderstorms in Perth, please read the storm summary.

 

Maximum temperature

2010 was one of the hottest years on record for most of the Perth Metropolitan area, apart from Rottnest Island. A number of sites observed their hottest year on record with annual mean maximum temperatures 1 °C to 1.5 °C above normal and mostly in the 24 to 26 °C range.

Perth Metro's annual mean daily maximum temperature in 2010 was 25.3 °C, which was the warmest year on record since records commenced in 1897. The previous record was 25.2 °C in 1978, whilst the third highest was 25.0 °C in 2009, so Perth Metro has recorded two of its three hottest years in the past two years. Daily maxima in 2010 at Perth Metro ranged from a very hot 42.9 °C on 17 January to a cool 13.3 °C on 9 July. During 2010, Perth Metro recorded 65 hot days (a hot day is when the daily maximum temperature is 32 °C or higher), which is the second greatest number of hot days behind the 66 days in 1978.

Heatwave conditions (three or more days of maximum temperature over 35°C) were observed at several Perth sites during summer 2009-10 and into the first two days of autumn: 2 to 5 January; 17 to 19 January; and 24 February to 2 March. During the second hot spell (17-19 January), Perth Airport recorded three days with daily maximum temperatures above 42 °C, which had only occurred once before at the airport (18 and 21 January 1961) since records began in 1944. Perth Metro recorded three days with daily maximum temperatures above 41.0 °C from 17 to 19 January. A run of three days over 41°C had happened on only two other occasions at the official Perth site since recording began in 1897 (13 to 15 March 1922 and 7 to 9 February 1933). The hottest temperature for 2010 at most sites was registered during this time, with Pearce RAAF recording the hottest daily maximum for the year in the Perth metropolitan area with 44.2 °C on 18 January 2010.

Spring in 2010 was notable for being the hottest on record for most sites in the Perth area, including Perth Metro and Rottnest Island, which both registered their warmest spring since records commenced in 1897. Medina Research Centre registered a daily maximum temperature of 41.4 °C on 19 November which was their highest spring temperature in 26 years of record.

Minimum temperature

Annual mean minimum temperatures in 2010 were near average in the Perth region, mostly in the 11 °C to 15 °C range. The annual mean minimum temperature at Pearce RAAF in 2010 was 0.6 °C cooler than normal, the biggest departure in the Perth area, whilst Perth Metro's annual mean daily minimum temperature in 2010 was 12.4 °C, which was 0.3 °C below normal.

Perth Metro recorded 12 warm nights during January 2010 (a warm night in Perth is when the overnight minimum temperature is 20°C or higher), which is equal to the record set in January 1995. The average for January is six. The the warmest night for the year at Perth Metro was 28.1 °C on 12 March, Perth Metro's second warmest March night on record, and eighth warmest night for any month.

Averaged over the three winter months of 2010, minimum temperatures were very much below average for most sites in the Perth area. Perth Metro, Pearce RAAF and Gosnells City registered their lowest mean minimum temperature for winter on record with a significant run of cold nights (nights with minima less than 5 °C) occurring during June and July across the Perth metropolitan area. Perth Airport recorded 15 consecutive cold nights from 24 June to 8 July, its longest run of cold nights in 66 years of record, and easily passing the previous record of 11 consecutive cold nights in winter 1990. Perth Metro recorded 37 cold nights (nights with minima less than 5 °C) during winter 2010, whch equalled the record for the Perth Metro (Mt Lawley) site set in 2001, and also included a record run of 15 consecutive cold nights from the 24 June to the 8 July. During this event, Perth Metro observed a very cold -0.6 °C on 26 June, which was its second coldest night on record behind the -0.7 °C on 17 June 2006; while Jandakot registered the coldest night in the metropolitan area in 2010 with -2.5 °C.

Wind & sunshine

Ocean Reef observed the highest wind gust for the Perth area in 2010 with 120 km/h at 1548 WST on 22 March during the March hailstorm.

Annual mean daily sunshine hours recorded at Perth Airport was 9.2 hours, which was the sunniest year since records commenced in Perth in 1898. The previous record was 9.1 hours in 1994.

Further information

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Extremes in 2010
Hottest day 44.2 °C at Pearce RAAF on 18 Jan
Warmest days on average 26.5 °C at Gosnells City
Coolest days on average 22.4 °C at Rottnest Island
Coldest day 9.8 °C at Bickley on 9 Jul
Coldest night -2.5 °C at Jandakot Aero on 26 Jun
Coolest nights on average 10.8 °C at Jandakot Aero
Warmest nights on average 15.7 °C at Rottnest Island
Warmest night 28.8 °C at Pearce RAAF on 18 Jan
28.8 °C at Swanbourne on 12 Mar
Wettest overall 599.6 mm at Mundaring
Driest overall 347.2 mm at Pearce RAAF
Wettest day 57.2 mm at Jarrahdale on 23 Mar
Highest wind gust 120 km/h at Ocean Reef on 22 Mar

Record lowest total annual rainfall
Total rainfall
for 2010 (mm)
Previous annual
lowest
Years of
record
Annual
average
Mundaring 599.6 653.4 in 1914 107 1072.4
Pearce RAAF 347.2 458.8 in 1969 42 658.5
Gosnells City 499.6 553.1 in 2006 41 830.5
Bickley 572.8 674.9 in 1969 39 1076.8
Jandakot Aero 495.8 509.8 in 2006 33 829.0
Medina Research Centre 487.1 513.8 in 2006 27 762.6



Record highest annual mean daily maximum temperature
Mean daily maximum
temperature
for 2010 (°C)
Previous annual
highest
Years of
record
Annual
average
Perth Airport 26.0 25.6 in 1999 65 24.4
Medina Research Centre 25.5 24.9 in 2009 20 24.2
Jandakot Aero 25.7 25.2 in 2009 18 24.3
Bickley 23.4 23.1 in 1994 16 22.4
Perth Metro* 25.3 25.0 in 2009 114 24.5
Swanbourne 24.9 24.3 in 1994 16 23.8
Gosnells City 26.5 26.0 in 2009 13 25.3



Record highest annual daily minimum temperature
Highest daily minimum
temperature
in 2010 (°C)
Previous annual
highest
Years of
record
Annual
average
Swanbourne 28.8 on 12 Mar 27.1 on 26 Feb 1997 18 13.8




Summary statistics for 2010
Maximum temperatures
(°C)
Minimum temperatures
(°C)
Rainfall
(millimetres)
Mean
for
2010
Diff
from
average
Highest
for
2010
Mean
for
2010
Diff
from
average
Lowest
for
2010
Total
for
2010
Average
annual
total
Rank
of
2010
Fraction
of annual
average
Bickley 23.4 +1.0 41.8 18 Jan 11.4 +0.3 2.4 25 Jun 572.8 1076.8 lowest 53%
Champion Lakes 25.1   41.5 17 Jan 13.6   2.7 4 Jul 446.2
Garden Island HSF 23.1   40.4 17 Jan 14.5   5.8 25 Jun 407.6
Gosnells City 26.5 +1.2 43.8 17 Jan     0.5 26 Jun 499.6 830.5 lowest 60%
Jandakot Aero 25.7 +1.4 43.0 18 Jan 10.8 -0.5 -2.5 26 Jun 495.8 829.0 lowest 60%
Medina Research Centre 25.5 +1.3 43.8 17 Jan 12.1 -0.1 0.0 26 Jun 487.1 762.6 lowest 64%
Pearce RAAF 26.3 +1.2 44.2 18 Jan 11.6 -0.6 -1.9 4 Jul 347.2 658.5 lowest 53%
Perth Airport 26.0 +1.6 43.2 18 Jan 11.9 -0.2 -1.0 3 Jul 483.2 774.2 v low 62%
Perth Metro* 25.3 +0.8 42.9 17 Jan 12.3 -0.4 -0.6 26 Jun 503.8 852.6 v low 59%
Rottnest Island 22.4 +0.4 41.1 17 Jan 15.7 +0.1 7.9 10 Jul 476.2 563.2 low 85%
Swanbourne 24.9 +1.1 42.9 17 Jan 13.5 -0.3 2.9 25 Jun 584.4 720.0 v low 81%

Notes

A Annual 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 5 pm on Tuesday 4 January 2011. 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.
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.

Records in this summary are based on sites with at least 10 years of data.

*Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Mt Lawley site, the most significant changes of this kind relate to minimum temperature and rain days.

For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Mt Lawley site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

For PDF files of Perth Metro climate statistics for other months, please click here for extremes and here for averages.

Further information

Media
(03) 9669 4057
Enquiries