Last updated
Was this helpful?
Last updated
Was this helpful?
NIWA Weather Files files were developed by the National Institute of Water and Atmospheric Research (NIWA) and subsequently reviewed and tested by technical specialists from the Building Research Association of New Zealand (BRANZ) and KΔinga Ora β Homes and Communities. The Ministry of Business, Innovation and Employment (MBIE) officially released the weather files in October 2024.
The TMY3 files represent typical climate conditions in Aotearoa New Zealand as of 2024, replacing the older TMY2 files created by NIWA in 2008.
A TMY3 file contains hourly weather data for an artificial year composed of 12 representative months. Each selected month is typical of that month's weather over a period of 10 years or more. These files are designed for:
Building energy and thermal performance analysis.
Demonstrating compliance with Building Code clause H1 Energy Efficiency, using modeling methods described in verification methods and .
The DSY1 files represent a year with a moderately warm summer, warmer than typical for the location, with an approximate return period of 7 years.
These files are specifically used to assess overheating risks in buildings. For example, the Chartered Institute of Building Services Engineersβ (CIBSE) technical memorandum outlines a design methodology for evaluating overheating risk in homes. Unlike TMY3 files, DSY1 files include a single year's observed data rather than synthesized data from multiple years.
These files contain detailed meteorological data collected from various weather stations and observation points. They typically include information on temperature, humidity, wind speed and direction, solar radiation, precipitation, and other atmospheric variables.
In addition to present-climate TMY3 and DSY1 files, NIWA provides future-projected weather files for three different climate change scenarios based on Intergovernmental Panel on Climate Change (IPCC) Shared Socioeconomic Pathways (SSP). These scenarios simulate potential climate conditions for specific timeframes:
M1 (SSP1-2.6 for 2040): Mean temperature increase: +0.5Β°C from present day (2024), or +1.5Β°C above pre-industrial levels.
M2 (SSP2-4.5 for 2050): Mean temperature increase: +1.0Β°C from present day (2024), or +2.0Β°C above pre-industrial levels.
M3 (SSP3-7.0 for 2070): Mean temperature increase: +2.0Β°C from present day (2024), or +3.0Β°C above pre-industrial levels.
The 18 climate zones align with territorial authority boundaries, except for the Rangitikei and Waitaki districts. These zones are subsets of the six climate zones defined in the acceptable solutions and verification methods for Building Code clause H1.
Each weather file is identified by a two-letter code in its file name, corresponding to the climate zone it represents. The map above illustrates the placement of these zones within the six H1 climate zones. The detailed breakdown is as follows:
βNLβ - Covers the Far North District, WhangΔrei District, and Kaipara District. Based on weather data from KaitΔia.
βAKβ - Includes Auckland and the Thames-Coromandel District. Based on weather data from Auckland.
βBPβ - Encompasses the Western Bay of Plenty District, Tauranga City, WhakatΔne District, Kawerau District, and ΕpΕtiki District. Based on weather data from Tauranga.
βHNβ - Covers the Hauraki District, Waikato District, Matamata-Piako District, Hamilton City, WaipΔ District, Εtorohanga District, South Waikato District, and Waitomo District. Based on weather data from Hamilton.
βNPβ - Includes the New Plymouth District, Stratford District, South Taranaki District, and Whanganui District. Based on weather data from New Plymouth.
βECβ - Encompasses the Gisborne District, Wairoa District, Hastings District, Napier City, and Central Hawkeβs Bay District. Based on weather data from Napier.
βMWβ - Covers part of the Rangitikei District south of 39Β°50'S (-39.83), the Manawatu District, Palmerston North City, Horowhenua District, and KΔpiti Coast District. Based on weather data from Paraparaumu.
βWNβ - Includes Porirua City, Hutt City, and Wellington City. Based on weather data from Wellington.
βNMβ - Encompasses the Tasman District, Nelson City, Marlborough District, and Kaikoura District. Based on weather data from Nelson.
βRRβ - Covers the Rotorua District. Based on weather data from Rotorua.
βTPβ - Includes the TaupΕ District, Ruapehu District, and the part of the Rangitikei District north of 39Β°50'S (-39.83). Based on weather data from TΕ«rangi.
βWIβ - Encompasses the Tararua District, Upper Hutt City, Masterton District, Carterton District, and South Wairarapa District. Based on weather data from Masterton.
βWCβ - Covers the Buller District, Grey District, and Westland District. Based on weather data from Hokitika.
βDNβ - Includes part of the Waitaki District on the true right of the Otekaieke River, Dunedin City, and the Clutha District. Based on weather data from Dunedin.
βCCβ - Encompasses the Hurunui District, Waimakariri District, Christchurch City, Selwyn District, Ashburton District, Timaru District, and Waimate District. Based on weather data from Christchurch.
βQLβ - Covers the Queenstown-Lakes District. Based on weather data from Queenstown.
βOCβ - Includes the Mackenzie District, the part of the Waitaki District on the true left of the Otekaieke River, and the Central Otago District. Based on weather data from Lauder.
βINβ - Encompasses the Southland District, Gore District, and Invercargill City. Based on weather data from Invercargill.
