HELSINKI, June 7 (Xinhua) -- While the risk of widespread blue-green algae blooms is lower than previous years, the warm weather in the past May might cause earlier blooms in northern part of the Baltic Sea, Finnish Environment Institute SYKE said on Thursday.

The peak of blue-green algae blooms in the Gulf of Finland occurs usually at the end of July and early August, and vast algae blooms will probably come earlier if the summer is warm, warned the institute.

Southern Scandinavia has experienced "hot" weather compared with the same periods in history due to the high pressure.

Finnish media said 13 straight days were recorded with mid-20 degree Celsius in May. According to the Finnish Meteorological Institute, the previous record was set in 1984 when there were 12 consecutive days in excess of 25 degrees Celsius.

The risk of blue-green algae blooms is high in western and central areas of the Gulf of Finland; the risk is moderate in the northern area of the main basin of the Baltic Sea, the Archipelago Sea and the southern areas of the Bothnian Sea; the risk is low in other parts of the Bothnian Sea and the Bay of Bothnia, said SYKE.

Harri Kuosa, head of unit at SYKE, said that weather conditions are a major factor affecting the situation of the blue-green algae.

"A warm summer allows more extensive algae blooms to form. Last year, high nutrient levels in the sea water did not lead to significant blue-green algae blooms because the summer was cold," he added.

SYKE said the general risk of algae blooms is lower than the last two years, as the algae have less nutrients available than before.

However, due to the refitting of the research vessel Aranda, much less nutrient information was obtained, and it remarkably increases the uncertainty of the prediction for the summer this year, said SYKE.

An algal bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is the result of the eutrophication of water bodies.

Among the algal blooms, blue-green algae blooms occur in the widest range, with the greatest harm and the most serious harm to human health.

Blue-green algae may form different types of toxins and agents that irritate the skin. Significant blue-green algae blooms should always be treated with caution, said SYKE.