Thursday 1 June, 2006

SEASONAL CLIMATE SUMMARY - WESTERN AUSTRALIAN REGIONAL OFFICE

Perth's second driest autumn on record

Rainfall: This autumn the rainfall in Perth was abnormally low. From March to May, Perth received 61.0 mm over 19 days compared with the average of 184 mm over 24 days. It was Perth's second driest autumn on record, surpassed only by the 42.4 mm in 1983. Last autumn, Perth recorded 271.2 mm over 32 days. Rainfall totals for individual months this autumn were: March 4.6 mm (average 20 mm), April 25.4 (average 44 mm) and May 31.0 mm (average 120 mm). The wettest days were 26 April and 15 May, on both of which 12.4 mm of rain was recorded.

Perth's top 10 driest autumns
Season	Rainfall (mm)	Rain Days	Ranking
1983	42.4	19	1
2006	61.0	19	2
1972	63.7	19	3
1914	66.8	25	4
1912	73.7	15	5
1959	79.3	26	6
1895	80.3	20	7
2000	81.2	16	8
1940	82.6	18	9
1903	85.5	33	10

Mean daily maximum temperature: The mean daily maximum temperature for Perth this autumn of 25.3 degrees Celsius was below the average of 25.8 degrees. Last autumn the mean daily maximum temperature was 26.2 degrees. Daily values this autumn ranged from a cool 16.6 degrees on 29 May to a very hot 37.9 degrees on 4 and 5 March.

Mean daily minimum temperature: The mean daily minimum temperature for Perth this autumn of 12.4 degrees Celsius was significantly below the average of 13.8 degrees. This was the lowest autumn mean daily minimum temperature yet recorded in the 13 years of measurements at the official Perth metropolitan observation site at Mt Lawley. Daily minima ranged from a cold 2.9 degrees on 25 May to a warm 24.6 degrees on 5 March. Last autumn the mean minimum temperature was 14.9 degrees.

* The wettest 24 hours to 9am this autumn occurred on the following dates: 26 April and 15 May 2006.

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:
Yanhui Blockley, John Cramb or Michelle Dal Pozzo, Climate Section, tel: (08) 9263 2222,office hours.