with John Maunder
It is considered that the homogeneous rainfall series described here is a fair and true record of what the rainfall would have been if the current observation site (Tauranga Airport) had been used since 1898, with the understanding that although standard accepted methodologies have been used, any adjustments are only estimates of what would have occurred if the location of the rainfall records had always been in the same place with the same surroundings and the same or similar recording gauge.
The methodology use in adjusting the older sites to the current observing site is published in the ‘NZ Meteorological Service Miscellaneous Publication’ No 180 in 1984.
In terms of climate change (such as is it getting wetter or drier, or warmer or colder), the methodology used in computing an ‘official’ set of climate observations is very important, as otherwise erroneous conclusions may be drawn.
The graph shows the range of rainfalls from an extreme high of 381 mm in 1925 to a low of 19 mm in 1906. There is a small decrease in the overall June rainfalls during the last 50 years, from 1961-2010, from an average of 126 mm, compared with an average of 139 mm during the 50 years from 1911-1960.
The rainfall in June 2019 was 51 mm, which was was the twelfth driest June in 120 years of recorded observations.
Since 1898, there have been 17 June months with a rainfall of 200 mm or more, and 11 June months with rainfalls of 50 mm or less.
In chronological order the wettest 17 June months are: 1915, 1917, 1920, 1925, 1930, 1935, 1939, 1943, 1946, 1961, 1968, 1971, 1981, 1985, 1997, 2010, and 2014.
By contrast the driest June months in chronological order are: 1906, 1913, 1914, 1933, 1942, 1958, 1959, 1967, 2001, 2012, and 2015.
For further information on range of climate matters see: https://sites.google.com/images/climatediceandthebutterfly/