Mean annual temperature for New Zealand, calculated from NIWA's 'seven-station' series. This series uses climate data from seven geographically representative locations. The data are adjusted to take account of factors such as different measurement sites (Mullan et al 2010). The blue and red bars show the difference from the 1981-2010 average. The black line is the linear trend over 1909 to 2015 (0.92 ± 0.26°C/100 years).