with John Maunder
Temperatures have been recorded in the Tauranga area at several sites during the last 100 years, including the current Tauranga Airport site from June 1990.
It's very common for areas such as Tauranga to have had different observation sites during the years; and the readings from the earlier sites have been adjusted to the present site using ‘standard climatological procedures'.
It's considered 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's 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 February temperatures for Tauranga is for the average daily maximum temperatures.
The graph above shows details of the average daily maximum temperatures (called simply ‘afternoon'), for Tauranga for February from 1913-2018.
The long-term average afternoon temperature in February for Tauranga is 23.8 degrees Celsius, ranging from the ‘cool' February months of 1934, with an average afternoon temperature of 21.6 degrees C , and 1921 with an average afternoon temperature of 21.8 degrees Celsius, to the ‘warm' February months of 1916 (26.4 degrees Celsius), and 1998 (26.2 degrees Celsius).
The graph of the average afternoon temperatures for February shows generally 'normal' variations from February to February.
The average afternoon February temperature for the 49 years from 1963-2011 of 24.0 degrees Celsius; this is just 0.3 degrees Celsius higher than the average afternoon February temperature for the 49 years from 1914-1962.
From 1914 to 2018, there have been six February months with an average afternoon temperature of 25.5 degrees Celsius or more, and six February months with an average afternoon temperature of 22.5 degrees Celsius or less.
The average afternoon temperature for February 2018 was 24.4 degrees Celsius, 0.3 degree C cooler than 2017.
The six ‘warmest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1916, 1928, 1954, 1955, 1998, and 2011.
In contrast the six ‘coolest' February months (in terms of afternoon temperatures) on record, in chronological order, are: 1921, 1931, 1934, 1940, 1976, and 2004.
For further information see the following textbooks books (all available at specialised libraries)
"The Value of the Weather" (1970), "The Uncertainty Business - Risks and Opportunities in Weather and Climate" (1986), "The Human Impact of Climate Uncertainty - Weather Information, Economic Planning, and Business Management " (1989),all by W.J.Maunder