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 23 September 2024
Next update due when there is a significant change of conditions or a new seasonal outlook.
Background
The El Niño/Southern Oscillation (ENSO) event responsible for the drought last summer gave place to a transition state with mixed signals in winter. Now, this climate driver is swinging back to a new La Niña phase. Winter brought some beneficial hydrological recovery to some dry areas of the Wairarapa, but mostly with an irregular spatial distribution with some areas partially missing out. The weather patterns throughout the season were very irregular with alternating flows and unusual winter thunderstorms, resembling an easter flow La Niña pattern at times.
Current situation
After a relatively wet winter, soil moisture levels are now back to around average for most of the region. However, as the solar radiation rapidly increases past the equinox, the Wairarapa in particular can quicky dry up under north-westerly flows. Rivers around the region are topped up after fierce late winter/early spring north-westerlies have been bringing plenty of rain, especially to the ranges. Likewise, groundwater levels are generally at their normal spring high, although reductions can occur quickly once irrigation begins, especially if combined with an early summer dry spell.
Meteorological outlook
International climate models are predicting that a reversal back to La Niña will likely take place throughout spring. In principle, we are expecting a relatively mild event. However, as the climate change signal naturally tends to amplify the La Niña circulation around New Zealand, it is likely that we will have significant warm season impacts. The expectation is to transition from a more westerly, drier regime for the Wairarapa spring initially, moving towards a more humid north-easterly flow later in the year. There is low confidence for the total seasonal accumulations at this stage, with likely irregular spatial distribution.
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.
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 - Winter 2024 summary Spring 2024 outlook
date_range Published 20 Sep 2024
Download now (PDF 1.9 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