Now available: Ocean temperature forecast shows if water is colder or warmer than expected

As the climate changes, our seas are getting warmer. A new forecast developed by the MetService-led Moana Project is now available on SwellMap, showing the difference between actual and expected sea surface temperatures for New Zealand waters. In science terms, this difference between actual and expected temperatures is called the ‘anomaly’. 
 
This 7-day forecast shows a map of the difference between actual and expected temperatures for that specific day of the year, with red colouring indicating warmer than usual conditions and blue colouring colder than usual conditions.   Users can click on the map to see the exact temperature differences for any location.

Image caption: SwellMap’s temperature anomaly map showing water temperatures in the Cook Strait are up 1.45°C above average on the 23rd of December 2022.

The sea surface anomaly forecast is based on 28 years of modelled data produced as part of the Moana Project. Based on this dataset, the expected sea surface temperature for any location and time of year was computed and compared to forecasted temperatures.  

Oceanographer Dr Joao de Souza from MetService says people can visit the site to see what is happening with ocean temperatures near them. 

“This year’s past temperatures have been consistently above average with marine heatwaves present in many regions around the country. This forecast allows people to check whether the water temperatures are indeed warmer or cooler than expected for the time of year,” says Dr de Souza. 
 
The new forecast complements existing ocean temperature forecasts available on SwellMap, which include temperatures at depth (100m, 200m, 1000m and sea floor) also available thanks to the Moana Project.