Skip to content

Drought check

http://www.gw.govt.nz/drought-check

Drought check

Updated 18 January 2018 8:29am

Current Situation

The Wellington region has been much drier and warmer than normal since October. November rainfall was generally less than 30% of average across most monitoring sites. December totals have been between 20 and 50% of average in the west and the Tararua Range, and about normal in eastern Wairarapa with a strong west-east gradient. Very low river flows were measured before Christmas (one in a five year minimum in some cases). Thanks to a couple of significant rainfall events, and very humid air masses with severe thunderstorms forming inland on several days, January rainfall so far is tracking well above average in the Wairarapa and normal to above average in Wellington and Kapiti. The soil moisture as of mid-January was above average for most of the eastern Wairarapa, but remained well below average on the Kapiti coast, where a ‘medium-scale adverse event’ was officially declared (https://www.beehive.govt.nz/release/early-dry-declared-adverse-event) before Christmas.  River levels have generally improved compared to mid-December. Most of the water take restrictions that were in place in December were lifted, but river levels remain generally low and with high rates of evaporation as a function of the elevated temperatures. 

Outlook

The blocking high pressure that was causing severe lack of rain early in the season has subsided, allowing a more “normal” La Niña pattern to kick in. La Niñas normally bring in hot weather and afternoon thunderstorms, especially around the ranges. Weaker westerlies are expected to continue, with more south-easterlies or north-easterly episodes with occasional bursts of very heavy rainfall either from localised thunderstorms or fuelled by cyclonic depressions intensifying over warm water. The rainfall recovery since Christmas has slightly reduced the risk of water shortages for the time being. River levels remain quite low but within what is expected for summer. The dry conditions improved in Kapiti but overall the soil remains very dry in the west. In the Wairarapa the soil is wetter than normal with favourable conditions for crops, even though the NIWA drought index still shows the region as dry because of the cumulative rainfall deficit. In short, the climate drivers suggest a mixed bag with heat waves, high humidity and potential major rainfall events, relatively cooler and wetter on the eastern coast (onshore winds), and much warmer than normal elsewhere.     

For the latest national drought index state, please visit: (https://www.niwa.co.nz/climate/information-and-resources/drought-monitor)  

Browse the data

Anomaly Maps

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

Click on links below to bring up the relevant anomaly map

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