Bathing water temperatures in the Helsinki metropolitan area can easily be found online

Kuusijärvi, Vantaa

The real-time temperatures of the waters of many beaches in the Helsinki metropolitan area can now be conveniently checked via an online service. In addition, people with programming skills can also use the temperatures published as open data as part of their own applications.

In 2020, more than a dozen beaches in the Helsinki metropolitan area were provided with a simple IoT sensor for their shoreline water, which transmits water temperature data directly online. The first remote sensor was installed at the Pikkukoski buoyancy pier in Oulunkylä in February 2020. Now there are also sensors in Helsinki, for example, in Hietaniemi, Vartiosaari and Marjaniemi. Sensors also show the temperatures in Espoo (Kattilajärvi and Hanika), as well as in Vantaa (Kuusijärvi and Vetokannas).

The web address of the UiRaS service for beach sensors updates the latest bathing water temperatures every few minutes. The page itself is purely informative and without any refinements, yet its tens of thousands of users prove that there is a demand for temperature data concerning beach locations. The number of users of the service has pleasantly surprised its creators.

"With just a little money and effort, a functional and popular service has been created. For example, lifeguards at Herttoniemenranta have praised the fact that they don't have to go and measure the temperature by hand every morning," says Aapo Rista, Senior Specialist at Forum Virium Helsinki, the servicebuilder.

Ease of service gains praise

The system's creators have been praised by sun worshippers and lifeguards, as well as winter swimmers and surfers in autumn storms. Previously, the measurement period was only scheduled for the summer season. Last year, the number of visitors to the site was at its highest during the early summer, when cold bathing waters caused those who had wished to swim to hesitate going to the beach.

“People have also started to request the temperature sensors to be placed on their favorite beaches. As recently as December 2020, we even took one sensor to Lauttasaari for a group of winter swimmers there," Rista says.

Bathing water temperature data rewarded as the best new open data creation in 2020

The sensors will also provide temperature data as open data for all interested parties, whilst a real-time interface is under construction for the service. The bathing water temperature data was selected by Helsinki Region Infoshare (, a joint open data service of the cities of the Helsinki metropolitan area, as the best new open data creatio in 2020. IoT sensors collect measurement data from waters automatically throughout the year. For the two-year time series found in the HRI service, the temperatures of water bodies can, therefore, be used in a variety of ways.

Temperature data can be found at:

Published: 4.6.2021 
(modified: )