with John Maunder
The graph below shows the range of Tauranga's December rainfalls, from an extreme high of 447 mm in 1962 to a low of only 4 mm in 1930.
The second wettest December was 2011, when 276 mm was recorded; and the second driest December was in 1994, when only 14 mm fell.
The rainfall for December 2016 was 44 mm.
The long-term average rainfall for Tauranga for December is 100 mm.
The graph of the December rainfall shows, at first glance, normal variations from year to year.
However, there has been an increase in December rainfalls during the last few decades. Indeed, the average December rainfall in Tauranga for the 50-year period from 1961-2010 of 109 mm, is 20 per cent higher than the rainfall for the 50-year period 1911-1960. In contrast the last two December months (2015, 2016) have had low rainfalls of 18 mm and 44 mm.
Since 1898, there have been eight Decembers with a rainfall of 200 mm or more, five of which occurred during the period 1962 to 2011. Seven December months have experienced rainfalls of 30 mm or less. Of significance are the high rainfalls in the consecutive December months of 1962 and 1963, of 447 mm and 224 mm respectively.
In chronological order, the eighth-wettest Decembers are 1924 with 225 mm, 1928 with 227 mm, 1936 with 240 mm, 1962 with 447 mm, 1963 with 224 mm, 1996 with 241 mm, 2001 with 208 mm and 2011 with 276 mm.
In contrast, the eighth-driest December months in chronological order are 1902 with 27 mm, 1912 with 22 mm, 1919 with 22 mm, 1930 with 4 mm, 1986 with 30 mm, 1990 with 21 mm, 1994 with 14 mm, and 2015 with 18 mm.
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