Candelo is a small town (pop. 400) located in the south-eastern corner of New South Wales, 22 km from the ocean.
The first official records of rainfall in Candelo were in April 1887. Rainfall data has been recorded continuously since then and still continues in 2011. Complete annual data is available for 119 years, with the only missing data (one month in each year) in 1997, 1999, 2003 and 2006. For these four missing months the monthly rainfalls have been estimated from the nearby (3 km) station at Kameruka. This has resulted in a record of 123 years of annual rainfalls at Candelo.
The graph of the annual rainfalls at Candelo shows that the rainfall has varied in cyclical patterns (generally every 10-15 years) over the past 123 years without any long-term trends to either increase or decrease. The average annual rainfall was 744 mm, but this has varied between 351 mm (in 2009) to 1492 mm (in 1934). The 2010 total was 868 mm - only slightly above average but still (just) the wettest year since 1992.
We all know the severity of the recent drought in south-eastern Australia. The graph shows that (at Candelo) its duration, extending from 1993, was its main feature. A somewhat similar drought period occurred between 1894 and 1918. In fact, apart for two years (1919 and 1934) conditions similar to the recent drought existed for an amazing 56 years between 1894 and 1949! On a somewhat brighter front, the 43-year period between 1950 and 1992 was generally above average rainfall. It would appear that since 1993 Candelo has returned to its pre-1950 rainfall pattern.
It is notable that there is no trend of “dry” years becoming “drier”, with 13 years having annual rainfalls between 350 and 450 mm.
Other stations on the south Coast with long periods of rainfall data include Bega and Moruya Heads. Both of these stations show very similar annual rainfall patterns to Candelo. The Bega data commenced in 1879 but has less complete data than does Candelo - in particular, since 2001 only two years of complete rainfall data exists. An automatic station in Bega has operated since 1994 but its data contains many malfunction errors and could not be used. The Moruya Heads data commenced in 1875 and has 135 years of complete annual rainfalls (1876-2010).
The monthly rainfall data used for the above analysis can be downloaded from the Bureau of Meteorology website: http://www.bom.gov.au/climate/data/index.shtml
LINKS TO OTHER RAINFALL ANALYSES
This article was written by Brian Gunter of Narooma, NSW. In his previous life Brian was an engineering hydrologist involved over many years in the analysis of rainfall and river flow data for the planning of water resources projects in Australia, Asia and Africa. In recent years he has been one of the volunteer weather observers of Marine Rescue NSW (formerly Royal Volunteer Coastal Patrol) who operate the Narooma station for the Bureau of Meteorology.
Prepared: 9 January 2011