with John Maunder
Rainfalls for the month of September have been recorded in Tauranga since 1898, except for 1904, 1907, 1908, and 1909.
The graph below shows the range of rainfalls from an extreme high of 274 mm in 1973 to a low of only 16 mm in 1965.
The second wettest September was in 1900, when 256 mm was recorded, and the second driest September was in 1944, when only 27 mm fell. The long-term average rainfall for Tauranga for September is 105 mm.
The graph of the September rainfall shows normal variations from year to year. Since 1898, there have been five Septembers with a rainfall of 200 mm or more (four of which occurred during the period 1900 to 1928, but there's only been one since then), compared with six September months with a rainfalls of 40 mm or less.
The rainfall for September 2016 was 166 mm, and the rainfall in September 2017 was 185 mm, was the tenth wettest September on record, and the wettest since 1973.
In chronological order, the ten wettest September months (rainfalls over 180 mm) are 1900,1912,1919,1923,1928,1946,1960,1969,1971,1973, and 2017.
In contrast the eleven driest September months (rainfalls of 50 mm or less) are 1910, 1913, 1914, 1921, 1922, 1944, 1965, 1993, 1987, 2006 and 2011.
The average rainfall for Tauranga for September for the 50 years 1961-2010 of 103 mm is similar to the rainfall for the previous 50 years (1910-1960).
For further information on a range of weather/climate matters see https://sites.google.com/site/climatediceandthebutterfly/