Finland’s ongoing heatwave is expected to persist through the weekend, potentially fueling more blooms.
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An aerial photo showing a cyanobacteria (blue-green algae) bloom in the Baltic Sea. Image: Gränsbevakningsväsendet
Cyanobacterial blooms, commonly known as blue-green algae, have increased significantly in Finland’s open marine areas, according to the Finnish Environment Institute (Syke).
The most notable growth has been reported in the eastern and central parts of the Gulf of Finland, as well as in the outer areas of the Archipelago Sea.
In contrast, the number of algae sightings in inland waters and along the coast has remained relatively stable. Syke noted that this pattern is typical for the end of July
Fresh observations taken on Wednesday indicated dense surface blooms throughout the outer coastal waters of the Gulf of Finland and in several inner coastal areas.
Syke emphasised that local conditions can change rapidly. Prolonged warm weather and calm winds favour the growth of blue-green algae and can cause deteriorated cells to accumulate at the water’s surface.
Hot weekend ahead, storms expected
The ongoing heatwave is expected to persist through the weekend, but the risk of scattered showers and thunderstorms is rising, particularly in the northern parts of the country.
Yle meteorologist Anne Borgström said that the end of the week will still be largely hot and sunny across Finland.
While Friday will bring more unstable conditions in the north, widespread rain is not expected. However, strong thunderstorm gusts are possible in southern Lapland.
Isolated thunder and rain showers could also occur in southwestern and eastern Finland, with the highest likelihood of storms in the north. Despite this, much of the country will continue to see dry and sunny weather with temperatures climbing near 30 degrees Celsius in many areas.
Saturday is also forecast to bring temperatures above the heat threshold (25 degrees), except in far northern Lapland. Thunderstorms may appear in western regions later in the day.
Both Friday and Saturday nights are expected to be tropical — meaning nighttime temperatures will not fall below 20 degrees — particularly in eastern Finland.
On Sunday, showers and thunderstorms will become more widespread, but hot weather will continue in the east, with highs around 30 degrees. Warm conditions are likely to extend into the start of next week.