Temperature: our changing climate
This section describes changes in New Zealand’s temperatures over time, and describes possible impacts on health.
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In New Zealand, NIWA has concluded that the mean annual temperature increased by 0.96°C between 1910 and 2010 (Figure 1).
Figure 1: Mean annual temperature in New Zealand has risen by 0.96°C over the past 100 years
In environmental health monitoring, temperature extremes are used in preference to mean temperatures, because they correlate more with health effects (see below).
We used NIWA weather data from around the country to determine which areas have high numbers of very cold and very warm days.
Warm days are more common in several isolated territorial authorities, particularly in the north and east of both main islands (movie 1).
Movie 1: Days over 25°C 2000-2017 by territorial authority, New Zealand
More cold days are experienced in the south than the north (movie 2).
Movie 2: Days under 0°C 2000-2017 by territorial authority, New Zealand
Download factsheet on temperature, climate change and health
Temperature changes affect our health.
Some temperature changes will benefit health. A decrease in the number of very cold days will mean fewer cold-related deaths and hospitalisations from cardiorespiratory (heart and lung-related) conditions.
However, any reduction in cold-related health effects is likely to be outweighed by a projected increase in heat-related death and illness . Heat can affect health in many ways, from a mild ‘heat rash’ to increasing death rates .
Temperature changes will affect vulnerable populations the most. See more about vulnerable populations on the 'who is more at risk' webpage.
Combining temperature data and population data shows us that Northland, the east coast of the North Island, and parts of the Bay of Plenty are likely to be regions where people are particularly affected by climate change.
Download factsheet on vulnerable populations and climate change
Information about the data
For more information about the data and indicators, download the metadata datasheets below:
- Datasheet: Number of days below 0 degrees, 2000-2013 (Jul 2014)
- Datasheet: Number of days over 25 degrees, 2000-2013 (Jul 2014)
- Datasheet: Notifications of cryptosporidiosis, giardiasis and salmonellosis, 1996 onwards (Jul 2014)
1. NIWA. 2010. 'Seven-station' series temperature data. Retrieved May 7, 2014, from www.niwa.co.nz/our-science/climate/information-and-resources/nz-temp-record/seven-station-series-temperature-data
2. Smith K, Woodward A, Campbell-Lendrum D, Chadee D, Honda Y, Liu Q, et al. 2014. Human health: Impacts, adaptation and co-benefits. In C Field, V Barros, D Dokken, K Mach, M Mastrandrea, T Bilir, M Chatterjee, K Ebi, Y Estrada, R Genova, B Girma, E Kissel, A Levy, S MacCracken, P Mastrandrea and L White (Eds.), Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel of Climate Change. Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press.
3. State of Victoria Department of Health. 2011. Heatwave plan for Victoria. Protecting health and reducing harm from heatwaves. Melbourne: Victorian Government.