National Weather Services

National Weather Services provides publicly available marine forecasts, mountain forecasts and the short forecasts for NZ.

• Four short forecasts are issued daily, covering the next two days, for all of New Zealand
• Two extended short forecasts are issued daily, covering the following three days
• Two brief forecasts are issued daily for the mountain areas of New Zealand

Protecting the Public

Warnings of Hazardous Weather Affecting Land Areas

Severe weather warnings are issued if the following weather is expected within the next day or so:

• Widespread heavy rain, exceeding 50 mm in 6 hours or 100 mm in 24 hours
• Widespread heavy snowfalls below 1000 metres on the North Island and 500 metres on the South Island, exceeding a depth of 10 cm in 6 hours or 25 cm in 24 hours
• Widespread severe gales with a sustained wind speed of 90 km/hr or more, or frequent gusts of 110 km/hr or more
• Heavy coastal swells, according to agreed criteria for certain regional authorities

Severe weather watches and outlooks are issued to provide earlier warning of such events.

Advisories may also be issued for less extreme weather which can still cause problems. One example is strong winds and cold rain in the South Island during lambing.

Definitions of the various warnings services can be seen - read our definitions here. An email subscription service for warnings is available.

Warnings are sent to the media and civil authorities in the affected area whenever a specified list of weather conditions is expected. These conditions include widespread heavy rain, or heavy snow to low levels, or very strong winds or gusts. Alerts may also be issued for damaging swells on the coast, or unusually high sea water (storm surge).

Warnings may be issued for less severe conditions if the region to be affected has recently suffered severe weather - such as in an area where more rain may increase risk of flooding.

Marine Forecasts and Warnings

• Warnings of gales, storms and hurricanes are issued as required for the Tasman Sea and a large part of the South Pacific Ocean, extending halfway to South America, and from latitude 25°S to 55°S (roughly 6% of the world's oceans)
• Twice daily, synopses and forecasts are issued for the same area
• Four times daily, detailed marine warnings and forecasts are issued for the coastal waters of New Zealand (up to 100 km from the coast) and the Chatham Islands (the precise areas covered for these coastal services are as specified in the New Zealand Nautical Almanac)
• Warnings of near gales (25 to 33 knots) are issued as required for the Auckland marine area - Manukau and Waitemata harbours and the Hauraki Gulf south of a line from Cape Colville to Bream Head.
• Four times daily, inshore marine forecasts are issued for the Bay of Islands, Auckland marine area, eastern Coromandel, Wellington Harbour and south coast, for Waitarere to Pukerua Bay, and for Pegasus Bay from the mouth of the Waimakariri River to Lyttelton Harbour
• MetService operates a radio-facsimile service broadcasting marine weather charts over the Pacific Ocean south of the equator
• MSL analysis and forecast charts are made available on the MetService web site

Emergencies

From time to time, emergencies may arise where specific users require urgent meteorological advice. The contract ensures that such advice will be available when needed. Such emergencies may include the need for weather information for national and international search and rescue operations, a fruit fly or a foot and mouth disease outbreak, volcanic eruptions and marine pollution incidents.

Meteorological Data Acquisition

Data Network

National Weather Services operates a comprehensive network which complies with recognised international standards as prescribed by the WMO over and around New Zealand. In particular, data are collected through...

• Surface observations over New Zealand
• Upper air observations using a variety of means (ground-based equipment, aircraft, satellites)
• Weather surveillance radars
• Ships
• A network of around seven drifting buoys in the Tasman Sea

Data Distribution and Availability

• Observational data from the Regional Basic Synoptic Network as defined by WMO is freely distributed internationally through WMO communications circuits with no restrictions on use
• Public access to a particular set of observational data is made available at no charge through MetService's Internet web site. Online New Zealand meteorological data for the last 24 hours includes:
  • Surface observation from at least 40 stations, updated 3 hourly;
  • All upper wind, temperature and humidity observations from New Zealand ground based stations;
  • Weather radar images from Auckland, Bay of Plenty, Gisborne/Hawke's Bay, Taranaki, Wellington, Canterbury and Southland, updated every 3 hours;
  • Weather satellite images covering the eastern Australia-Tasman Sea-New Zealand region, updated every 3 hours.
  
  
• All observational data gathered in direct support of forecast services provided under the contract is passed to NIWA for archiving in the National Climate Database.

Support Services to the Pacific

• MetService continues to maintain close links with the meteorological agencies of various Pacific Island states and, as far as possible, to monitor the quality and integrity of data gathered from the Pacific Islands, and provide appropriate technical advice.
• All warnings of hazardous weather for the South Pacific region, normally received from the Nadi Tropical Cyclone Warning Centre, are forwarded to Radio New Zealand International and to the Ministry of Foreign Affairs and Trade.
• MetService provides backup for the main warnings and forecasting responsibilities of the Nadi Tropical Cyclone Warning Centre, should that Centre temporarily shut down or be cut off, possibly due to a direct hit by a cyclone.

World Meteorological Organization

All weather forecasting relies on international co-operation and exchange of data. The world's National Meteorological and Hydrological Services work with the World Meteorological Organization (WMO), the United Nations System's authoritative voice on weather, climate and water. Their combined efforts are essential for the maintenance and improvement of global weather observations, meteorological services and meteorological research and for ensuring their contributions to the protection of life, property and the environment and to sustainable development.

The Chief Executive of MetService or his designate is the Permanent Representative of New Zealand with WMO.

MetService's National Weather Services sends data gathered from the New Zealand region to other WMO member countries around the world. This is used as input to sophisticated computer models at major centres such as London and Washington. These build pictures of the world weather, and forecast how weather patterns should change over the next week or more. Information from these models is sent back to MetService and used as the basis for many of the weather forecasts we issue.