From Sunday 29 September 2024, the Canterbury Weather Radar will be undergoing replacement. To allow for this work, the radar is scheduled to be offline for two and a half to three months. This is part of our ongoing investment in the New Zealand weather radar network, funded through our contract with the Ministry of Transport.

The project involves replacing the existing concrete tower and building a new foundation, tower and two small ancillary buildings as well as the installation of a new upgraded weather radar and radome featuring the latest dual polarisation technology. The new radar will provide improved services to communities in the Canterbury region, aviation, defence, emergency services and maritime safety as well as some high-level coverage into Otago and Marlborough.

The Canterbury Radar is located on a small hill in Rakaia which means that that any upgrade work will be dependent on the weather conditions. We have chosen this time of year for the more likely extended periods of settled weather which are typical of mid spring/start of summer.

Our expert team will continue to deliver accurate weather information using a wide range of data sources, including weather models, satellites, weather balloons, and automatic weather stations.

While the radar undergoes its replacement, composites of radar coverage from the Wellington, Otago, and Westland radars will provide partial coverage of the area covered by the Canterbury Radar.

The new Canterbury Radar is scheduled be in service before the end of the calendar year.

Frequently asked questions

Q. Why are you replacing the radar?

A. This piece of observational infrastructure has served us well for more than 30 years, with technology and infrastructure advancements, it is time for an upgrade. The project involves a new tower, new ancillary buildings and new radar technology. The new radar will provide enhanced information particularly during severe weather in the Canterbury region as well as some high-level coverage into Otago and Marlborough. This will be particularly helpful for emergency services, councils and those involved in aviation and maritime safety.

Q. How long will the radar be offline?

A. The Canterbury radar will be offline from 29 September and is expected to return to service mid-December, however, the work is weather dependent.

Q. What are the benefits of the new upgraded radar compared to the current one?

A. Replacing the 30-year-old technology of the current radar with the latest dual polarisation technology will provide benefits such as being able to identify different types of precipitation, be it rain, hail or snow. This more detailed information means our meteorologists will have a much clearer picture of what’s happening in the atmosphere during a weather event.
Other benefits include:

• Better understanding of when we have hail present within a storm, when there is a mix of rain and snow, and what height of the freezing level is.
• We can leverage the new technology to correct for ‘attenuation’ – an effect that weakens the signal after it passes through a storm close to the radar. – Correcting for this gives us a better picture of a more distant storm when heavy precipitation is also closer to the radar.
• The new radar will be more sensitive and give a clearer picture of what’s happening in the atmosphere within its observing range.

Additionally, the new tower has been engineered to be more resilient, abiding to latest earthquake standards. All our steel tower designs are IL3. You can find out more about this here.

Q. Why is the radar located in Rakaia and not on the Port Hills?

A. The existing radar has operated since early 1992 in Rakaia and the current site is still very suitable.

We want our radars to have the best view of the lower atmosphere (from the ground up to the top of the troposphere about 15km high) both near to and away from the radar (covering a distance of 300 km from the radar). This isn’t possible in hilly terrain where hills and mountains could block what the radar can see. Therefore, we tend to install the radar on the top of a hill to get a clear view of the horizon (or as much as possible) such as at the Wellington and Otago radars.

Thanks to the flat Canterbury plains the current Rakaia site offers the best view possible over the city and it also has a great view of storms approaching Christchurch from the south.

Q. How do you forecast severe thunderstorms without a radar?

A. Forecasting severe thunderstorms requires many tools of which radar is one.

Other tools we use to diagnose and/or forecast severe thunderstorms, and often in combination with each other:

• Satellite imagery
• Surface observations: Wind, rain, webcams, human observations
• Weather balloons (Radiosondes)
• Lightning detection networks
• Sea level pressure chart analysis
• Computer models
• Forecaster experience and 

  climatology

Q. Will the radar being offline impact severe weather forecasting?

A. Our team of expert meteorologists use a range of data sources to inform their forecasts, including weather models, satellites, weather balloons, and automatic weather stations.

While the radar is offline, services will be somewhat affected during an event as this piece of observational infrastructure is a useful tool to observe how the event is progressing. Composites of radar coverage from the Wellington, Otago, and Westland radars will provide partial coverage of the area usually covered by the Canterbury Radar. It’s also worth noting that radar imagery is not used before the event, i.e. before the rain starts. In the days leading up to an event, Severe Weather Outlooks, Watches and Warnings are issued using other observational data sources to analyse the storms before they arrive, including weather models and the expertise of our meteorologists.

Q. What frequency does the radar operate under?

A. The current radar has operated since February 1992 and transmits on 5.605 GHz. The new radar will be licensed to operate on the same frequency.

Our radar installations comply with RF standards for their operation, as stipulated in our radio frequency license issued by Radio Spectrum Management – see www.rsm.govt.nz