Climate change projections for the Wellington and Wairarapa region

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

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 3.0˚C warmer by 2090.

By 2090, Wellington is projected to have from 6 to 40 extra days per year where maximum temperatures exceed 25 degrees, with around 5 to 13 fewer frosts per year.

Rainfall

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

Seasonal projections show that in winter Paraparaumu is likely to experience 5 to 13 per cent more rainfall by 2090 while Masterton is likely to experience up to to 7 per cent less rainfall.

According to the most recent projections, Wellington and Wairarapa are not expected to experience a significant change in the frequency of extreme rainy days as a result of climate change.

Wind

The frequency of extremely windy days in Wellington by 2090 is likely to increase 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.

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 is due for release in 2017.

Impacts by season

By 2090, the region could expect*:

Spring
  • 0.6°C to 2.7°C temperature rise
  • 3 per cent less to 2 per cent more rainfall in Masterton
  • 1 to 3 per cent more rainfall in Paraparaumu

Summer

  • 0.7°C to 3.1°C temperature rise
  • 1 per cent less to 8 per cent more  rainfall in Masterton
  • 1 to 2 per cent more rainfall in Paraparaumu

Autumn

  • 0.7°C to 3.1°C temperature rise
  • No change to 3 per cent more rainfall in Masterton
  • 1 to 3 per cent more rainfall in Paraparaumu

Winter

  • 0.7°C to 3.2°C temperature rise
  • 7 per cent less to 1 per cent more rainfall in Masterton
  • 5 to 13 per cent more rainfall in Paraparaumu

*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 Wellington and the Wairarapa?

Coastal hazards – The Wellington region is particularly vulnerable to even a small rise in sea level because of its small tidal range. There may be an increased risk to coastal roads and infrastructure from coastal erosion and inundation, increased storminess and sea-level rise.

Heavy rain – The capacity of stormwater systems may be exceeded more frequently due to heavy rainfall events which could lead to surface flooding. River flooding may also become more frequent, particularly in low-lying areas. Floods are likely to become more intense.

Erosion and landslides – More frequent and intense heavy rainfall events are likely to lead to more erosion and landslides.

Droughts – By 2090, the time spent in drought for the Wellington region and the Wairarapa in particular ranges from minimal change through to more than double, depending on the climate model and emissions scenario considered. More frequent droughts are likely to lead to water shortages, increased demand for irrigation and increased risk of wild fires.

Biosecurity – Climate change could lead to changes in pests and diseases over time. A likely increase in weed species and subtropical pests and diseases could require new pest management approaches. Regional biodiversity may be threatened by changing temperature and rainfall patterns, and sea level rise.

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, water shortages and 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 

Greater Wellington Regional Council’s climate change information [Greater Wellington Regional Council website]

Reviewed:
30/06/16