IrriMet: Soil moisture + accurate weather forecast = better irrigation decisions

IrriMet is NIWA’s new state-of-the-art online decision-support tool that helps you irrigate with the right amount at the right time, and avoid leaching and waste.

IrriMet tells you at a glance—via your computer, laptop, tablet or smartphone—whether irrigating is beneficial, or wasteful and potentially harmful, based on your actual and forecast soil moisture balance.

It also tells you how much money you risk wasting on energy and other costs if you irrigate more than you need to.

IrriMet helps you improve pasture growth and avoid leaching and waste by ensuring you irrigate with the right amount at the right time, and fertilize or spray effluent only when maximum benefit will be gained.

NIWA IrriMet from NIWA on Vimeo.

IrriMet uses soil moisture and weather data from the nearest station in NIWA’s extensive climate monitoring network.

The data is fed in real-time to NIWA’s supercomputer and combined with our high-resolution weather forecasts and information you provide on your farm’s soil properties and drainage characteristics.

IrriMet forecasts how much water will enter your root zone from rainfall, and how much will leave via evapotranspiration and drainage – and how quickly. From these inputs and outputs, IrriMet calculates your soil moisture balance up to a week ahead.

IrriMet then translates this balance into simple ‘tick’ (irrigation is beneficial) and ‘cross’ (irrigation is wasteful and potentially harmful) daily guidance. When a tick is showing, IrriMet puts you in charge of planning daily irrigations that will top up rainfall and maintain your soil moisture at a desired level.

You can see instantly the effect your planned irrigations will have on your soil moisture balance, via IrriMet’s easy-to-read charts.

And when there’s too much rain, IrriMet alerts you to the risk of wasting water and leaching nutrients if you decide to irrigate, fertilize or spray effluent. 

IrriMet is your at-a-glance aide to making critical irrigation, fertilizing and effluent-spraying decisions based on real-time soil conditions and accurate weather forecasts.

IrriMet fact file

  • Guidance for irrigation need and leaching risk shown for today and next seven days.
  • Detailed graphs show soil moisture gains and losses, and overall balance, from six days ago to seven days ahead.
  • Enter planned irrigations and see instantly how they will affect your soil moisture balance.
  • Soil moisture data drawn from the nearest monitoring station in NIWA’s network.
  • Highly localised weather forecasts driven by NIWA’s industry-leading high-resolution forecasting computer model.
  • Forecasts and guidance automatically updated four times daily.
  • Manage separate irrigation schedules for up to six paddocks on one IrriMet account.
  • Handy effluent application record-keeper included.
  • Purchase a 12 month subscription online in five easy steps.

More information

Go to for more information and to subscribe. 


Our goal is for Irrimet to enhance irrigation and effluent-spraying decisions based on real-time conditions. [Credit: Ross Woods]
NIWA’s supercomputer greatly enhances business management with new forecasting accuracy. [Dave Allen]