Climate change projections for the Waikato region

Map of Waikato region. This page provides an overview of how the climate in the Waikato region is likely to change into the future and what implications this has for the region.

Projections of climate change depend on future greenhouse gas emissions, which are uncertain. There are four main global emissions scenarios ranging from low to high greenhouse gas concentrations. This page presents regional projections as a range of values from a low emissions to a high emissions future.

The projected changes are calculated for 2031–2050 (referred to as 2040) and 2081–2100 (2090) compared to the climate of 1986–2005 (1995).

Temperature

Compared to 1995, temperatures are likely to be 0.7˚C to 1.1˚C warmer by 2040 and 0.7˚C to 3.1˚C warmer by 2090.

By 2090, the Waikato is projected to have from 10 to 60 extra days per year where maximum temperatures exceed 25˚C. The number of frosts could decrease by around 5 to 13 days per year in Waikato, with frosts becoming rare in the Coromandel.

Rainfall

Rainfall will vary locally within the region. The largest changes will be for particular seasons rather than annually.

Winter rainfall in Ruakura is projected to increase by 4 to 8 per cent by 2090. In Taupo, winter rainfall is projected to increase by 4 to 7 per cent by 2090. Spring rainfall is projected to decrease by up to 6 per cent in both locations.

According to the most recent projections, the Waikato is not expected to experience a significant change in the frequency of extreme rain days as a result of climate change.

Wind

The frequency of extremely windy days is likely to decrease by 2 to 3 per cent. There may be an increase in westerly wind flow during winter, and north-easterly wind flow during summer.

Storms

Future changes in the frequency of storms are likely to be small compared to natural inter-annual variability. Some increase in storm intensity, local wind extremes and thunderstorms is likely to occur.

The frequency of ex-tropical cyclones is projected to either decrease or remain unchanged over the 21st century; however the ex-tropical cyclones will likely be stronger and cause more damage as a result of heavy rain and strong winds. 

Sea-level rise

New Zealand tide records show an average rise in relative mean sea level of 1.7 mm per year over the 20th century. Globally, the rate of rise has increased, and further rise is expected in the future.

The Ministry for the Environment provides guidance on coastal hazards and climate change, including recommendations for sea level rise, see Preparing for coastal change: A guide for local government in New Zealand.  An updated edition will be published in late 2016.

Impacts by season

By 2090, the region could expect*:

Spring
  • 0.6°C to 2.7°C temperature rise
  • 6 per cent less to 2 per cent more rainfall in Ruakura
  • 6 per cent less to 1 per cent more rainfall in Taupo

Summer

  • 0.7°C to 3.3°C temperature rise
  • 2 to 4 per cent more rainfall in Ruakura
  • No change to 8 per cent more rainfall in Taupo

Autumn

  • 0.7°C to 3.2°C temperature rise
  • 3 per cent less to 2 per cent more rainfall in Ruakura
  • 1 to 3 per cent more rainfall in Taupo

Winter

  • 0.7°C to 3.1°C temperature rise
  • 4 to 8 per cent more rainfall in Ruakura
  • 4 to 7 per cent more rainfall in Taupo

*Projected changes are relative to 1995 levels. The values provided capture the range across all scenarios. They are based on scenario estimates and should not be taken as definitive. For more information, see the full report on climate projections.

What could this mean for Waikato?

Drought – By 2090, the time spent in drought ranges from minimal change through to more than double, depending on the climate model and emissions scenario considered. Parts of the Hauraki district, Matamata and Thames-Coromandel are especially likely to experience increased drought risk.  More frequent droughts are likely to lead to water shortages, increased demand for irrigation and increased risk of wild fires.

Flooding – More heavy rainfall will increase the risk of inland flooding in the west and in river catchments in the Coromandel. Rising sea levels and storm surge will increase the risk of salt-water intrusion in low-lying coastal areas.

Erosion and landslides – More frequent and intense heavy rainfall events are likely to lead to more erosion and landslides, as much of the soil in the region is volcanic and prone to erosion.

Disease – Tropical diseases may become established in areas where they currently do not exist.

Biosecurity – Warmer, wetter conditions (particularly in the south and west of Waikato) could increase the risk of invasive pests and weeds.

Lakes – Higher temperatures and changes in rainfall are likely to result in higher lake levels, on average, in western and central parts of New Zealand such as Lake Taupo. Warmer water temperatures could lead to more algal blooms, a reduced range of trout and the spread of pest species like carp.

Agriculture – Warmer temperatures, a longer growing season and fewer frosts could provide opportunities to grow new crops. Farmers might benefit from faster growth of pasture and better crop growing conditions. However, these benefits may be limited by negative effects of climate change such as prolonged drought, reduced water availability, increased flood risk, or greater frequency and intensity of storms.

The Ministry for Primary Industries website and associated Climate Cloud website have more information on the regional impacts of climate change on agriculture.

Find out more

Waikato Regional Council's climate change information [Waikato Regional Council website]

Reviewed:
30/06/16