Weather Eye with John Maunder

Temperatures have been recorded in the Tauranga area at several sites over the last 100 years including the current Tauranga Airport site from June 1990.

It is very common for areas such as Tauranga to have had different observation sites over the years and the readings from the earlier sites have been adjusted to the present site using "standard climatological procedures".

It is considered that the temperature series described here is a fair and true record of what the temperature would have been if the current observation site (Tauranga Airport) had been used throughout the period.

It is important to note, that in considering 'climate change”, the methodology used in computing an ‘official' set of climate observations is very important as otherwise erroneous conclusions may be drawn.

Traditionally, temperature observations have been recorded with a set of maximum and minimum temperature thermometers. These record the daily maximum temperature (usually recorded in mid-afternoon), and daily minimum temperature (usually recorded just before dawn).

This analysis of temperatures for Tauranga are those for the average daily maximum temperatures. Later analyses will be for the average daily minimum temperatures.

The graph shows details of the average daily maximum temperatures (called simply "afternoon" from now on), for Tauranga for May from 1913-2012. Note that April 1947 is not included because of incomplete data.

The long-term average afternoon temperature in May for Tauranga is 16.9 degrees C, ranging from the "cool" May months of 1936, 1940, 1949 with an average afternoon temperature of 14.9 degrees C, to the "warm" May months of 1916 (19.3 degrees C), 2010 (19.1 degrees C), and 2007 (18.9 degrees).

The graph of the average afternoon temperatures for May shows generally "normal" variations from May to May.

However, the last 20 May months were a little "warmer" than other May months since 1913.

From 1913 to 2012, there have been 10 May months with an average afternoon temperature of 18 degrees or more, and 11 May months with an average afternoon temperature of less than 16 degrees. The value for May 2013 was 18.5 degrees, the fifth warmest on record.

The 12 "warmest" May months (in terms of afternoon temperatures) on record, in chronological order, are 1916, 1928,1938, 1950,1999, 2000, 2003, 2005, 2007, 2010, and 2013.

In contrast, the 11 "coolest" May months (in terms of afternoon temperatures) on record, in chronological order, are 1913, 1920, 1924, 1936, 1940, 1945, 1959, 1967, 1977, 1983, and 1992.

The average afternoon temperature in May during the period 1914-1962 was 16.7 degrees, compared with 17.1 degrees from 1993 to 17.1 degrees from 1993 to 2011.

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