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.

Diagram showing the typical El Niño impacts in NZ: warm waters flow east, cooler sea temperatures, and more westerly winds
Typical El Niño impacts in New Zealand. Credits: Weatherwatch

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:

Browse the data

Anomaly Maps

How different has recent rainfall/soil moisture been compared with the same time in previous years?

30 Day Rainfall Anomaly

90 Day Rainfall Anomaly

1 Day Soil Moisture Anomaly

30 Day Soil Moisture Anomaly

 

Site-specific graphs

Cumulative rainfall/soil moisture totals for indicator sites compared with historical averages and other recent years. 
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
Updated February 8, 2024 at 3:22 PM

Get in touch

Phone:
0800496734
Email:
info@gw.govt.nz