A brief summary of climate and hydrological conditions in the region.
This service is regularly updated during periods in which closer monitoring is required (regardless of time of the year), in recognition that there is potential for dry spells, or irregular hydrological recharging. It does not define an official council position on drought or drought declaration. Outside of dry periods, less frequent updates synchronise with our latest seasonal outlooks.
Updated 7 February 2024
Next update due when there is a significant change of conditions or a new seasonal outlook.
Background
The current El Niño/Southern Oscillation (ENSO) has matured and is now expected to start to decline towards autumn. This has been a highly unusual, or ‘non-traditional’ El Niño. On the diagram below we can see that normally El Niños are associated with cooler oceanic temperatures around New Zealand.
However, the waters remained very warm with high evaporation, and the weather patterns resembled a mix between what would have been a traditional El Niño, and a La Nina. This means that mixed wind flows and residual easterly rainfall events are still occurring in a random fashion.
Current situation
While December was still within normal to wetter than normal in the upper ranges, January was dry overall and very dry in the south and east. GWRC rainfall anomaly maps are showing only 40-60% of normal rainfall. The national drought index, which is updated daily (see below), is indicating the region to be very dry as a whole and extremely dry in some areas such as the southern coast and northeastern Wairarapa Valley.
As our river flows are highly dependent on the short-term rainfall in the catchments, below normal flows or even ‘meteorological drought’ conditions can manifest relatively quickly (within a month), in the absence of significant rain at this time of the year. Regular rain falling in parts of the Tararua Range has kept the main Wairarapa rivers topped up and low flow restrictions for irrigators have been avoided so far (even though average monthly river volumes were relatively low). However, valley floor streams are at sustained summer low flows and restrictions have been in place throughout January for some water users. Furthermore, February will likely be the driest month of the season. As such, close monitoring is recommended.
Meteorological outlook
International climate models are predicting that the current El Niño has matured and will progressively start to decline towards autumn. However, there is usually a lag in the atmospheric response and it’s looking likely that things will get drier (i.e., a more traditional El Niño response) before improving again. February could potentially be the driest month of the season, but overall, the climate models are not predicting a very extreme dry February-to-April season, as a whole.
Climate change
The ‘normal’ longer-term water balance is becoming increasingly hard to maintain quite possibly due to climate change influences, and increased high frequency climate variability, with more unreliable weather patterns. Droughts are expected to become more severe and frequent in the Wellington region, particularly in the Wairarapa.
Even if international climate policy efforts were to successfully contain global warming under 1.5-2 degrees (the Paris Agreement’s ambition), it is important that we enhance our water resilience and be prepared for more unreliable climate patterns with both extreme dry and extreme wet periods. We note that the warming of the land also means that evapotranspiration will greatly increase, so the soil will likely need more ongoing rain to maintain ideal moisture levels, compared to what it has needed in the past.
While the last three years have been incredibly wet thanks to a persistent La Niña, there is some evidence that our soils are getting drier, and groundwater storage may be decreasing, in the long-term.
View the latest national drought index state
View the national drought forecasting dashboard
View the latest seasonal report:
Climate drivers and seasonal outlook for the Wellington Region - Spring 2023 summary Summer 2023-2024 outlook
Spring 2023 was a mixed bag for the region, alternating between strong westerly flow typical of El Niños and north-easterly rain events typical of La Niñas. Total rainfall accumulations were… Read more here
date_range Published 11 Dec 2023
Download now (PDF 2.2 MB) get_appBrowse the data
Anomaly Maps
How different has recent rainfall/soil moisture been compared with the same time in previous years?
Site-specific graphs
Area | Rainfall | Soil Moisture |
Kapiti Coast (lowland) | Otaki at Depot | |
Kapiti Coast (high altitude) | Penn Creek at McIntosh | |
Porirua | Horokiri Stream at Battle Hill | |
Wellington City | Kaiwharawhara Stream at Karori Reservoir | |
Hutt Valley (upper catchment) | Hutt River at Kaitoke Headworks | |
Upper Hutt | Upper Hutt at Savage Park | Upper Hutt at Savage Park AQ |
Wainuiomata | Wanuiomata River at Wainui Reservoir | |
Wairarapa (high altitude) | Waingawa River at Angle Knob | |
Wairarapa Valley (north) | Kopuaranga River at Mauriceville | |
Wairarapa Valley (Masterton) | Ruamahanga River at Wairarapa College | Wairarapa College AQ |
Wairarapa Valley (south) | Tauherenikau River at Racecourse | Tauherenikau River at Racecourse |
Wairarapa (north-eastern hills) | Whareama River at Tanawa Hut | Whareama River at Tanawa Hut |
Wairarapa (south-eastern hills) | Waikoukou at Longbush | Waikoukou at Longbush |
Get in touch
- Phone:
- 0800496734
- Email:
- info@gw.govt.nz