Free access to rainfall intensity dataset
People will now be able to access rainfall intensity data for free thanks to funding from the Ministry for Cities, Environment, Regions and Transport (MCERT).
What this means
The High Intensity Rainfall Design System (HIRDS) is an online tool developed by Earth Sciences New Zealand that estimates the magnitude and frequency of heavy rainfall across New Zealand. HIRDS provides a map tool which enables rainfall intensity estimates for any location in New Zealand.
Funding from MCERT means people will now be able to access the tool and underlying datasets for free and for any purpose under a creative commons (CC BY) license.
Commercial use of the dataset, including for engineering design and consultancy for public infrastructure, previously attracted a charge.
HIRDS is currently being updated to version 5. This update includes rainfall augmentation factors based on 2024 New Zealand climate projections, along with a reanalysis of extreme values using all available historical data and an updated methodology. The updated version will be made freely available when this work is completed in October 2026.
Why this matters
The dataset allows planners and engineers to understand the frequency and magnitude of high-intensity rainfall events, supporting them to design resilient stormwater, transport and other flood-sensitive infrastructure.
Increasing access to this data is in line with the first pillar of the Government's National Adaptation Framework, which focuses on ensuring that information about the risks from natural hazards like floods and storms is readily available. This data will also be a key input into flood hazard information used in the New Zealand Flood Map, which is a key component of the National Adaptation Framework.
See High intensity rainfall statistics tables (NIWA website)