Wettest May for thirty-one years in Perth

Rainfall above average: The city received 191.2 millimetres of rainfall over 16 days in May, compared with the average of 119 mm over 12 days, which is the wettest May since the 200.2 mm in 1974. Historically, May rainfall has ranged from 14.1 mm in 1964 to 308.1 mm in 1879. Last May Perth recorded 103.2 mm over 12 days. Total rainfall for January to May this year was 274.2 mm compared with the average of 205 mm, making it the wettest start to the year since the 294.4 mm in 1990. The highest daily rainfall in May 2005 occurred on the 2nd with 50.4 mm, which is the wettest day in May since the 52.4 mm on 13 May 1988.

Mean daily maximum temperature above average: Perth's mean daily maximum temperature in May was 23.3 degrees Celsius, compared with the average of 22.3 degrees. This was the highest mean maximum for May since the 24.0 degrees in 2003, and the fourth highest for May on record. Daily maxima ranged from a mild 18.4 degrees on the 24th to a warm 29.6 degrees on the 10th.

Mean daily minimum temperature equal record: Perth's mean daily minimum temperature in May was 13.8 degrees Celsius compared with the average of 10.8 degrees. This equals the highest value for May for Perth since records began in 1897. A mean daily minimum temperature of 13.8 degrees was also recorded in 1972. Minima ranged from a cool 9.3 degrees on the 24th to a warm 18.8 degrees on the 10th.

Mean daily sunshine hours below average: Perth's mean daily sunshine hours in May was 6.1 hours which was below the average of 6.7 hours.

May monthly mean temperature and sunshine
Element	2005	Long- term Average	Highest	Year	Lowest	Year	Records Commence
Maximum Temperature (°C)	23.3	22.3	24.0	2003	18.7	1931/56	1897
Minimum Temperature (°C)	13.8	10.8	13.8	1972	8.8	2000	1897
Sunshine (hours per day)	6.1	6.7	7.9	2000	3.4	1905	1898
May monthly rainfall and rain days
Element	2005	Long-term Average	Highest	Year	Lowest	Year	Records Commence
Rainfall (mm)	191.2	119	308.1	1879	14.1	1964	1876
Rain days	16	12	25	1921	5	1913	1876

May daily extremes
Element	2005	Date	Extreme	Date	Records Commence
Highest daily maximum (°C)	29.6	10/05/2005	34.3	01/05/2002	1897
Lowest daily maximum (°C)	18.4	24/05/2005	11.5	23/05/1995	1897
Highest daily minimum (°C)	18.8	10/05/2005	20.8	01/05/1983	1897
Lowest daily minimum (°C)	9.3	24/05/2005	1.3	11/05/1914	1897
Wettest 24 hours to 9am (mm)	50.4	02/05/2005	76.2	17/05/1942	1876

* Denotes the lowest minimum temperature for June on record on the following dates: 19 June 2003 and 2 June 2004.

Warm days in June: On average, Perth can expect eleven days when the maximum temperature is 20 degrees or more. The greatest number of such days in June was 21 days in 1983. Last June, Perth recorded thirteen such days.

Cold days in June: On average, Perth can expect one day when the maximum temperature is 15 degrees or less. The greatest number of such days in June was 10 in both 1931 and 1955. Last June, Perth recorded no such days.

Cold nights in June: Perth has a mean of six cold nights when the minimum temperature is 5 degrees or lower. The greatest number of such nights was in 2001 with twelve. Last June, Perth recorded one such night.

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 Glen Cook tel: (08) 9263 2222 on weekdays.