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 27 March 2024

Next update due when there is a significant change of conditions or a new seasonal outlook.


The current El Niño/Southern Oscillation (ENSO) event is almost over. 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 for most of summer. The weather patterns have been a mixed bag with alternating flows, and severe thunderstorms which would not normally occur in El Niño years.

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

The total summer rainfall in the region was about half the long-term average for most places, but rainfall was closer to normal for Upper Hutt, Kāpiti and the northwestern part of the Tararua Ranges. The eastern Wairarapa was one of the driest spots, with total accumulations only between 20 and 40% of the seasonal average. This pattern has remained mostly unchanged throughout March. The national drought index, which is updated daily (see below), is indicating most of the region to be very dry (except the Kāpiti Coast).  Thanks to regular (albeit modest) showers and reduced evapotranspiration as we passed the equinox with cooler temperatures, the more severe areas previously classed as ‘extremely dry’ have eased slightly. Soil moisture deficit levels are comparable to 2020 and 2021, but not as severe as 2020 for the most part.

After maintaining relatively good baseflows throughout summer, several larger rivers in the Wairarapa (including the Ruamāhanga, Waingawa, Pahaoa and Mangatarere) have fallen below minimum flows in the past week, meaning restrictions for irrigators and other water users have come into force. Several other rivers are close to minimum flow and most of the valley floor streams have been at very low flow (with water users under restriction) for several months now.  Given the time of year and forecast for the next couple of weeks, restrictions in the larger (Tararua-fed) rivers may not be prolonged or sustained. However, the broader meteorological outlook (see below) suggests a good likelihood of dryness in the Wairarapa persisting for some time yet, especially to the east; this means the valley floor streams and eastern hills rivers could remain low.

Meteorological outlook

International climate models are predicting that the current El Niño will dissipate towards the end of autumn. A La Niña might start forming during winter (about 60% chance according to NOAA), but it’s still too early to make a firm prediction considering typically poor skills of most ENSO models this time of the year. Regardless, there is usually a lag in the atmospheric response to the climate drivers. It’s looking likely that the Region will remain drier than average for a little longer before returning to normal. The extended climate projections are currently suggesting a 40-50% chance that rainfall could remain below average in the eastern Wairarapa until May-June, before progressively returning to normal into winter and beyond.

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 April 19, 2024 at 2:46 PM

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