Thursday 1 September, 2005

SEASONAL CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

Another drier than normal winter in Perth

Rainfall: Winter rainfall this year was below average. From June to August, Perth received 438.4 millimetres over 45 days compared with the average of 485 mm over 50 days. Last winter, Perth recorded 411.4 mm over 52 days. Rainfall totals for individual winter months were: June 251.0 mm (average 179 mm), July 62.8 mm (average 171 mm) and August 124.6 mm (average 135 mm). The wettest day was 7 June 2005 when 52.2 mm of rain fell.

Mean daily maximum temperatures: The mean daily maximum temperature for Perth this winter of 18.3 degrees Celsius was close to the average of 18.6 degrees. Daily values ranged from a cold 11.5 degrees on 12 June to a warm 24.8 degrees on 1 August. Last winter the mean daily maximum temperature was 18.4 degrees. Perth recorded 7 cold days this winter, when the maximum temperature was 15 degrees or less, which is three days above the long-term average of four days, and the greatest number of such days for winter since 1998.

Mean daily minimum temperatures: The mean daily minimum temperature for Perth this winter was 7.9 degrees, slightly below the average of 8.4 degrees. Daily minima ranged from a cold 0.2 degrees on 7 and 12 July to a mild 15.4 degrees on 4 June. Last winter the mean minimum temperature was also 8.4 degrees.

Mean daily sunshine hours: Perth's mean daily sunshine hours this winter was 6.2, which was close to the long term average of 6.3 hours.

Winter mean temperature and sunshine
Element	Winter 2005	Long term Average	Highest	Year	Lowest	Year	Records Commence
Maximum Temperature (°C)	18.3	18.6	19.7	1976/1983	16.5	1916/1956	1897
Minimum Temperature (°C)	7.9	8.4	11.0	1964/1983	6.6	2001	1897
Sunshine (hours per day)	6.2	6.3	7.2	2001	4.1	1926	1898
Winter rainfall and rain days
Element	Winter 2005	Long term Average	Highest	Year	Lowest	Year	Records Commence
Rainfall (mm)	438.4	485	957.1	1945	260.0	1940	1876
Rain days	45	50	68	1915/1926	35	1902	1876

Winter daily extremes
Element	Winter 2005	Date	Extreme	Date	Records Commence
Highest daily maximum (°C)	24.8	01/08/2005	28.1	05/06/1975	1897
Lowest daily maximum (°C)	11.5	12/06/2005	8.8	26/06/1956	1897
Highest daily minimum (°C)	15.4	04/06/2005	18.7	12/06/1988	1897
Lowest daily minimum (°C)	0.2	7 & 12/07/2005	0.0	*Twice	1897
Wettest 24 hours to 9am (mm)	52.2	7/06/2005	99.1	10/06/1920	1876

*Denotes the lowest daily minimum temperature on the following dates: 15 July 1997 and 27 July 1998.

Past winters in Perth 1994-2005
Season	Mean Maximum (°C)	Mean Minimum (°C)	Total Rainfall (mm)	Rain Days	Mean Sunshine (hour)
1994	18.9	8.7	535.0	51	6.3
1995	18.3	8.6	512.4	52	6.1
1996	18.6	9.7	555.8	63	5.6
1997	18.8	7.6	361.6	41	6.9
1998	18.2	8.5	414.8	57	5.7
1999	19.2	8.6	401.6	48	6.7
2000	18.5	9.0	497.2	58	6.0
2001	19.1	6.6	382.2	42	7.2
2002	18.8	8.7	384.8	51	6.3
2003	18.3	7.8	464.4	51	6.1
2004	18.4	8.4	411.4	52	6.3
2005	18.3	7.9	438.4	45	6.2

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 Re lf (JR), or Glenn Cook tel: (08) 9263 2222 on weekdays.