Water temperature 26.5.2023

Surface water temperature measurement is in progress at nearly all observation stations

Due to the sunny and warm weather, surface water temperatures were 1–5 degrees warmer than average at all stations in operation on Thursday 25 May. The coming cooler period and windy weather might cool down the surface water, as the surface layer of the water that warmed up in early summer remains thin.

On Friday 26 May, the surface water temperature had already fallen below the average in the time period, especially at Kyrölahti in Lake Näsijärvi and at the Päijätsalo observation station in Lake Päijänne. In Southern Finland, the surface water temperature varied between 14 and 17 degrees Celsius, in Central Finland between 12 and 16 degrees Celsius and in Lapland between 7 and 10 degrees Celsius. The warmest surface water, around 16 degrees Celsius, was found in Lake Pyhäjärvi in Säkylä and in Lake Ala-Rieveli in Heinola. Surface water temperature is measured at 8 in the morning at the depth of 20 cm.

Nuori iloinen poika ui järvessä.

How is surface temperature of water measured?

The surface temperature of water varies significantly depending on the season and weather. Temperatures are measured daily in lakes, rivers and the sea during the ice-free season, and the results are available without delay.

Lakes and rivers

The surface water temperatures of lakes and rivers are measured at 34 monitoring stations, and temperature data are available from 80 sites in total. The measurements come from automated instruments placed at the depth of 20 centimetres close to the shore, and the results are available in almost real time. The official reference value is the reading recorded every day at 8:00 a.m.

Marine areas

At sea, surface water temperatures are measured from a depth of 20 to 30 centimetres using buoys. Water temperature data are also obtained from sea water level monitoring stations which operate round the year. Their measurements are taken at a depth of two to three metres, however, and the results cannot be compared to the readings from the buoys.

Fun facts about water temperature