A meteorologist at Foreca, Joanna Rinne, is warning nighttime swimmers about the potential for rapidly approaching thunderstorms across Finland. The upcoming Midsummer weekend carries a risk of experiencing one of the most intense thunderstorm days of the year. A cold front is expected to move over Finland between Saturday night and Sunday, fueled by a warm, humid air mass preceding it. This combination creates ideal conditions for thunderstorm development. Foreca advises caution for those planning to swim at night, as the storms could arrive unexpectedly. The approaching weather system poses a potential hazard for outdoor activities during the holiday period.