An average of six people drown each Midsummer weekend in Finland, with warmer weather typically bringing higher numbers.
Last year the highest mortality was seen in eastern Finland, including Savo and North Karelia.
The regions with the highest average mortality are South Savo and Southwest Finland, which both had 10 drowning deaths last year.
By the end of May this year, at least 13 individuals had drowned in eastern Finland, including two in South Savo, an area with many holiday homes.
Life vests could prevent 80% of drownings
Altogether 40 drowning deaths were reported nationally in the first five months of this year.
The summer months have the highest death toll, particularly on warm weekends.
More than half of those who died were drunk and not wearing personal flotation devices. Rescue officials estimate that up to 80 percent of drownings could be prevented by the use of such devices.
Last year's Midsummer weekend brought six drownings, the same as the long-term average, according to the Finnish Swimming Teaching and Lifesaving Federation. The last Midsummer recorded in Finland without any drownings was 47 years ago.