Climate change projections for the Auckland region

Map of Auckland region. This page provides an overview of how the climate in the Auckland region is likely to change in 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 0.9˚C warmer by 2040 and 0.7˚C to 3.1˚C warmer by 2090.

By 2090, Auckland is projected to have from 11 to 70 extra days per year where maximum temperatures exceed 25˚C, and frosts are likely to become rare.

Rainfall

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

Spring rainfall in Warkworth is projected to decrease by 1 to 13 per cent by 2090. In Mangere, spring rainfall is projected to decrease by up to 10 per cent by 2090.

There is large natural variability in extreme rainfall frequency in the Auckland region from year to year and decade to decade. According to these latest projections, Auckland is 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 Auckland by 2090 could decrease by up to 5 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 is due for release in 2017.

Impacts by season

By 2090, the region could expect*:

Spring

  • 0.6°C to 2.8°C temperature rise
  • 1 to 13 per cent less rainfall in Warkworth
  • No change to 10 per cent less rainfall in Mangere

Summer

  • 0.7°C to 3.3°C temperature rise
  • 2 to 5 per cent more rainfall in Warkworth and Mangere

Autumn

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

Winter

  • 0.7°C to 3.0°C temperature rise
  • 1 per cent less to 2 per cent more rainfall in Warkworth
  • 1 to 5 per cent more rainfall in Mangere

*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 Auckland?

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 and hill country erosion events may also become more frequent.   

Coastal hazards – Coastal roads and infrastructure may face increased risk from coastal erosion and inundation, increased storminess and sea-level rise.

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. More frequent droughts are likely to lead to water shortages, increased demand for irrigation and increased risk of wild fires.  The frequency and intensity of El Niño events, which are associated with periods of drought in Auckland, may increase.  Increased drought frequency coupled with windier conditions may lead to an increase in the occurrence of fires.

Agriculture – Warmer temperatures, a longer growing season and frosts becoming rare could provide opportunities to grow new, sub-tropical crops and 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 water supply issues, prolonged drought, increased flood risk, or greater frequency and intensity of storms.

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

Biosecurity – Climate change could result in an increased incidence of invasive pests, affecting both pasture and horticultural crops. Several existing pest species could become more serious pests with even a slight increase in temperature.

Disease - There may be an increase in the occurrence of summer water-borne and food-borne diseases such as Salmonella. There could also be an increased risk from some vector-borne diseases such as Dengue Fever and Ross River Virus.

Find out more

Auckland Council's climate change webpage [Auckland Council website]

Reviewed:
30/06/16