Science Centres: Atmosphere

This is the home for NIWA's UV and ozone research, including maps and graphs showing daily predictions and measurements for UV levels across New Zealand.

UV Index at Lauder

See all our UV forecasts

This information is provided by NIWA free of charge and can be used only for personal use. Repackaging and on-selling in any form is prohibited.

What is the UV Index (UVI)?

The UV index is a standard measurement of erythemal (sun-burn causing) UV intensity that gives a more objective measure than the old “time to burn” (which cannot account for skin tone). The scale is open-ended, but a UV index of greater than 10 is extreme and a UV index of less than 3 is low. For clear skies, the UVI depends mainly on the sun elevation angle and the ozone amount, view here. The UVI also depends on cloud cover, sun-earth separation, altitude, pollution, and surface reflections (e.g., snow cover). The highest values in the world occur in the tropics at high altitudes, where the UVI can exceed 25. The geographical and seasonal variation in peak UVI for New Zealand can be viewed here. In the NZ winter, the UVI rarely exceeds 3. Because of differences in ozone, sun-earth separation and pollution, the peak UVI in NZ is approximately 40% greater than at comparable latitudes in the Northern Hemisphere.

Current UVI at specific NZ sites

Graphs showing predicted and measured UV Index at several sites in New Zealand at which data from UV monitors maintained by NIWA are updated at 15 minute intervals. Model predictions including forecast cloud effects are included.

New Zealand Ozone and UVI Maps for noon (12:00NZST, 0:00GMT)

The maps provided here are forecasts modelled on available satellite ozone data.

Yesterday's UVI measured at specific sites in NZ and the South Pacific

Graphs showing predicted and measured UV Index at Leigh, Paraparaumu, Christchurch, Lauder, Invercargill and Rarotonga are updated daily.

Today's UVI forecasts for Specific Sites

Graphs showing UVI forecasts specific sites in New Zealand and the South Pacific region. When the UVI is low (less than 3), no protection is required and short exposures to sunlight will be beneficial for vitamin D production. At all other times some protection to avoid sunburn is recommended. The "UV Sun Protection Alert Period" is defined as the period when the clear sky forecast is greater than UVI = 3, a level at which damage to fair skin can occur in less than 1 hour. When the UVI = 12, damage to fair skin can occur in less than 15 minutes. For darker Polynesian skin types the safe exposure periods can be doubled. Further details on UV and health are provided by the Cancer Society's Sunsmart and Sunsmart Schools and by the Health Sponsorship Council.

Lauder Ozone

A graph of daily ozone measurements at Lauder over this year compared with past years (climatological variability). Ozone column amounts are measured in Dobson Units (DU), where 1 DU = 2.69 x 10¹⁶ molecule/cm².  

Data availability

• Ozone time series for any global site can be extracted from the NIWA Assimilated Total Column Ozone database.

• Ozone, cloud transmission, total radiation and various biological weightings of UV radiation can be extracted for approximately 100 sites in the New Zealand region using the NIWA UV Atlas.

• Erythemally-weighted UV irradiances (UV Index values) from Lauder and several other sites in the New Zealand region can be extracted from the NIWA Climate database. Select Datatype/Daily and Hourly Observations/Sunshine and Radiation/UV radiation to access historical 10-minute mean UVI values. These data are available from the same sites as plotted above for Yesterday's UVI, as specified in the site-selection menu.

• UV radiation data (and trace gas data) from Lauder compared with other global sites can be accessed from the international Network for the Detection of Atmospheric Composition Change (NDACC).

• Other radiation data, including aerosol optical depths from Lauder compared with other global sites can be accessed from the international Baseline Surface Radiation Network (BSRN).

• UV data from Lauder compared with other North American locations can be accessed from the US Department of Agriculture (USDA). 

Assessments of Ozone Depletion and its Effects

NIWA scientists contribute to regular international assessments of ozone depletion and its environmental impacts, as required under the terms of the Montreal Protocol on Protection of the Ozone Layer. These assessments include responses, in simple layman's terms, to Frequently Asked Questions (FAQs).

• Our understanding of the science of ozone depletion is assessed by the World Meterological Organisation (WMO) Scientific Assessment Panel.

• The environmental impacts of ozone depletion and its interactions with climate change are assessed by the United Nations Environment Programme's, Environmental Assessment Panel (UNEP EEAP). 

The NIWA UV Atlas

The aim of the UV Atlas project is to produce maps and time series of parameters describing the UV radiation environment over New Zealand since 1960. Maps are produced for the area around New Zealand (34° to 48° S, 166° to 180° E), and time series are produced at sites where broadband radiation measurements are available. Click for more information on the:

• outputs produced by this project

• details on how to obtain the data

• access to data viewing software and its documentation. 

UVI Displays

NIWA has developed UVI Displays for the public that record current levels of UV. For more information please contact Richard McKenzie ( r.mckenzie@niwa.co.nz ).

Personal UV Dosimeters

There is widespread public interest in the relationships between UV radiation and health. The effects of UV on health can be harmful – as in its effect on skin cancer rates, or beneficial – as in the case of its effect on vitamin D status. In the past, researchers have attempted to determine these relationships as functions of ambient UV radiation. However, the UV doses that humans are typically receive are less than 5% of that available UV. Read more about personal UV dosimeters. 

Latest All-Sky Image at Lauder, New Zealand

The all-sky image shows a hemispheric view of the sky at Lauder. These images record the cloud cover at Lauder for use in the atmospheric radiation research. The images are updated every 10 minutes and an archive image is available for each of the last 24 hours.

NIWA Assimilated Total Column Ozone

The assimilated total column ozone database that was developed at NIWA provides global daily total column ozone by combining measurements from a number of different satellite-based instruments. Offsets and drifts between the different datasets are resolved through comparisons with the Dobson and Brewer ground-based instruments and through inter-satellite instrument comparisons. The database is now maintained by Bodeker Scientific, and can be accessed from here.