Record dry and warm conditions so far in May for western WA

Very dry and warm conditions have been recorded in west coast parts of WA in May and in some locations these conditions have persisted for much of the year so far. The following west coast cities and towns have been affected:

Carnarvon - 10 consecutive days with a maximum temperature of 30ºC or greater, between 1 and 10 May 2009. This is Carnarvon's longest run of 30ºC or greater days in May since records commenced in 1907. The previous record was 7 days between 1 and 7 May 1955. Carnarvon has also recorded 30ºC or greater temperatures on 12 days this month, equalling its highest occurrence of 30ºC or greater days in May. Carnarvon has previously recorded 12 days of 30ºC or greater in May in 1994 and 2006.

Kalbarri - Driest year to date on record, with no measurable rainfall recorded in 2009 so far. The long dry spell commenced on 3 December 2008, making it a record dry spell of 164 days without measurable rainfall. The previous driest year up to 15 May was 1985 with 8.2 mm, whilst the previous longest dry spell at Kalbarri, since records commenced in 1970, was 162 days in 1986/1987.

Geraldton - Driest year to date with 2.6 mm recorded between 1 January and 15 May. The previous driest year up to 15 May was 2007 with 15.8 mm. Rainfall recording commenced in Geraldton in 1877.

Perth - Equal driest May to date. Perth has recorded no measurable rainfall up to 15 May, and this has occurred on only two other occasions previously, in 1926 and 1994. Rainfall records commenced in Perth in 1876. With fine weather forecast across the weekend, Perth will have had it's driest start to May in 134 years if no rainfall is recorded by 9am Saturday 16 May.

Much warmer than normal conditions have also been recorded in Perth so far in May. Maximum temperatures up to 14 May dictate that Perth has experienced its 3rd warmest start to May, 2nd warmest autumn to date, and 2nd warmest start to a year since temperature recording commenced in 1897.

Bunbury - Record run of 50 days without measurable rainfall, from 27 March 2009 to 15 May 2009. The previous record was 46 days from 24 Febuary 1950 to 10 April 1950. Daily rainfall recordings are available for Bunbury from 1907.

Weather patterns in May have seen a stationary high pressure ridge over southern WA as weak cold fronts slip to the south. Thus fine warm weather has prevailed, particulary over west coast parts of WA, where mean maximum temperatures are currently up to 6°C warmer than normal for May in some locations. The only parts of WA to see any rainfall so far this month have been south coast districts.

These record warm and dry conditions continue the long warming and drying trend that the southwest of Western Australian has experienced over the last century. Research by the Bureau of Meteorology and CSIRO has shown that this warming and drying is linked to a combination of the enhanced greenhouse effect, ozone depletion and natural variability.

Further information:
John Relf (JR), Yanhui Blockley or Neil Bennett - tel: (08) 9263 2222.