Blue-green algae monitoring
In summer 2026, the Finnish Supervisory Agency monitors the presence of cyanobacteria, i.e. blue-green algae, and informs about the algae situation every second week until mid-August. In June, the Finnish Environment Institute published the risk assessment of cyanobacterial blooms in open sea areas, but institute’s traditional weekly cyanobacterial reviews will not be published. Monitoring the blue-green algae situation and water quality in official bathing areas and providing information about them through their channels is up to the municipalities.
Risk prediction 2026
Current blue-green algae situation at Järvi-meriwiki
Check the situation. Report your own observations. At Järvi-meriwiki.fi.
Algal reviews from earlier year
2025
Summary of blue-green algae monitoring
Risk prediction 2025
Algal reviews 2025
During the summer 2025, national cyanobacterial reviews were published weekly on Thursdays from 19 June to 7 August.
2024
Risk prediction
Algal reviews
- The number of blue-green algae observations has increased slightly in inland waters and on the coast of Southwest Finland 2024-08-08 (sttinfo.fi)
- Windy and rainy weather has curbed blue-green algae blooms in lakes and sea areas 2024-08-01 (sttinfo.fi)
- Relatively small amount of blue-green algae have been observed in inland waters, but there are plenty of observations on the coast and in the open sea 2024-07-25 (sttinfo.fi)
- Blue-green algae observations have increased in coastal and open sea areas 2024-07-18 (sttinfo.fi)
- Slight increase in blue-green algae observations in inland waters 2024-07-11 (sttinfo.fi)
- The blue-green algae situation has remained stable since last week, unstable and windy weather slows down the growth of blue-green algae 2024-07-04 (sttinfo.fi)
- Warm weather has increased blue-green algae observations in inland waters, on the coasts and in the Gulf of Finland area 2024-06-27 (sttinfo.fi)
- Earlier-than-usual observations of blue-green algae in marine areas, situation in inland waters typical for early summer 2024-06-20(sttinfo.fi)
- In sea areas, the risk of extensive blue-green algae blooms remains significant 2024-06-10 (sttinfo.fi)
Summary review
2023
Risk prediction
Algal reviews
- Blue-green algae situation has calmed down at sea and in lakes 2023-08-31 (sttinfo.fi)
- Reduced wind increases surface blooms of blue-green algae 2023-08-24 (sttinfo.fi)
- Blue-green algae situation has remained stable both in lakes and at sea 2023-08-17 (sttinfo.fi)
- Strong winds have dispersed blue-green algae surface blooms in inland waters and at sea 2023-08-10 (sttinfo.fi)
- Unstable weather has kept the blue-green algae situation calm in lakes, surface blooms observed at sea 2023-08-03 (sttinfo.fi)
- The blue-green algae situation has deteriorated in marine areas and inland waters 2023-07-27 (sttinfo.fi)
- Windy weather has restrained blue-green algae blooms 2023-07-20 (sttinfo.fi)
- Warm weather has increased the number of blue-green algae observations in inland waters and sea areas ;2023-07-13 (sttinfo.fi)
- Cool and rainy weather has kept the blue-green algae situation calm on lakes and at sea 2023-07-06 (sttinfo.fi)
- The blue-green algae situation has deteriorated significantly in inland waters and coastal areas, also abundant blue-green algae in sea areas 2023-06-29 (sttinfo.fi)
- Blue-green algae observations increased in inland waters and at sea during Midsummer week 2023-06-22 (sttinfo.fi)
- Blue-green algae observations increased slightly in inland waters and coastal areas 2023-06-15(sttinfo.fi)
- The blue-green algae situation calm both in the Baltic Sea and in lakes 2023-06-08 (sttinfo.fi)
- Summer algae forecast: Warm and calm weather conditions can lead to powerful blooms of blue-green algae in the Baltic Sea 2023-06-01 (sttinfo.fi)
Summary review