Wednesday 1 March, 2006

SEASONAL CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

Perth's coolest summer since 1959/60

Rainfall: This summer the rainfall in Perth was above average. From December to February, Perth received 54.0 mm over 14 days compared with the average of 34 mm over 8 days. It was the wettest summer since the 146.2 mm in the summer of 1999/2000 and included the most rain days since records commenced at the Mt Lawley observation site in 1993. Last summer, Perth recorded 5.6 mm over 6 days. Rainfall totals for individual months this summer were: December 5.0 mm (average 13 mm), January 28.4 (average 9 mm) and February 20.6 mm (average 12 mm). The wettest day was 7 February when 18.0 mm of rain fell.

Mean daily maximum temperature: The mean daily maximum temperature for Perth this summer of 27.8 degrees Celsius was well below the average of 30.3 degrees. This was the lowest summer mean daily maximum temperature since the summer of 1959/60, then 27.6°C. Last summer the mean daily maximum temperature was 30.0 degrees. Daily values ranged from a mild 19.7 degrees on 5 December to a very hot 40.1 degrees on 21 February. A maximum temperature of 32 degrees or higher was reached on only 24 occasions this summer whereas the average for summer is 31 such days.

Mean daily minimum temperature: The mean daily minimum temperature for Perth this summer of 16.2 degrees Celsius was also below the average of 17.4 degrees. This was the lowest summer mean daily minimum temperature yet recorded at the official Perth metropolitan observation site at MT Lawley. Daily minima ranged from a cool 8.9 degrees on 24 December to a warm 24.9 degrees on 21 February. Last summer the mean minimum temperature was 16.7 degrees.

Mean daily sunshine hours: Perth's mean daily sunshine hours this summer was 10.5 hours which was below the long term average of 11.5 hours and was the lowest summer sunshine hours since the 9.8 hours in summer in the of 1991/92.

Summer mean temperature and sunshine
Element	Summer 2005/06	Long term Average	Highest	Year	Lowest	Year	Records Commence
Maximum Temperature (°C)	27.8	30.3	32.0	1977/78	26.4	1901/02	1897
Minimum Temperature (°C)	16.2	17.4	20.3	1977/78	15.4	1901/02	1897
Sunshine (hours per day)	10.5	11.5	12.2	1997/98	8.7	1922/23	1898
Summer rainfall and rain days
Element	Summer 2005/06	Long term Average	Highest	Year	Lowest	Year	Records Commence
Rainfall (mm)	54.0	34	180.4	1954/55	0.8	1974/75	1876
Rain days	14	8	20	1913/14	2	3 years	1876

Summer daily extremes
Element	Summer 2005/06	Date	Extreme	Date	Records Commence
Highest daily maximum (°C)	40.1	21/02/2006	46.2	23/02/1991	1897
Lowest daily maximum (°C)	19.7	05/12/2005	14.9	17/12/1952	1897
Highest daily minimum (°C)	24.9	21/02/2006	29.3	3 years *	1897
Lowest daily minimum (°C)	8.9	24/12/2005	8.4	02/12/2002	1897
Wettest 24 hours to 9am (mm)	18.0	07/02/2006	120.6	09/02/1992	1876

* The highest summer minimum temperature of 29.3 degrees has occurred on the following dates: 6 February 1898, 8 February 1933 and 3 February 1962.

Note: 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 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.

Further information:
John Relf (JR), or John Cramb tel: (08) 9263 2222 on weekdays.