Fifteen decades of climate record
The New Zealand instrumental air temperature record goes back to 1853 and provides us with a valuable indication of how the climate has changed since the mid 19th century.
The figure below shows the mean temperature anomaly for spring (green), summer (yellow), autumn (pink), and winter (blue) for each decade from the 1850s. Note that the first and last decades are incomplete. The line traces the all-season average anomaly over the period, from –0.54 in 1853–60 to +0.54 in 2001–03.
Winter temperatures appear to have changed the most over this period, from –0.74 to +0.84, a change of more than 1.5 °C.
Mountain mists on a warm winter’s day near Hanmer. June air temperatures at Hanmer were 2.6 °C above average.