Enjoying a sunny summer day at Munkkiniemi beach in Helsinki on 12 July 2025. Photo: Heikki Saukkomaa / Lehtikuva
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Finland recorded its hottest day of the summer on Saturday as temperatures exceeded 30 degrees Celsius in several regions, prompting widespread heat warnings. At the same time, thunderstorms and heavy rain swept across southern parts of the country, bringing a sharp contrast to the intense heat.
The highest reading was reported at Joensuu’s Linnunlahti station, where the temperature reached 30.3°C. Earlier in the day, Porvoo’s Harabacka station recorded 29.9°C. Other locations exceeding 29°C included Hyvinkää, Salo, Vantaa, Liperi, Pyhtää, Mäntsälä and Virolahti.
The previous summer high of 29.0°C had been observed in Jämsä in mid-June.
Meteorologists from the Finnish Meteorological Institute (FMI) confirmed that the current warm air mass covering the country is responsible for the extreme temperatures. Forecasts suggest the hot conditions will persist through Sunday and Monday, with heat warnings extended to nearly all regions except the far north.
Northern Ostrobothnia and the Tornio River Valley were identified as the areas most likely to see temperatures surpass 30°C again on Sunday. In central and southern Finland, temperatures of 26–29°C remain common.
The intense daytime heat was followed by a tropical night across parts of the country. At the Katinen station in Hämeenlinna, temperatures did not drop below 20°C overnight. According to FMI, a night is classified as tropical in Finland when the temperature remains above 20°C between 9 p.m. and 9 a.m.
The upcoming night from Sunday to Monday is also expected to meet the tropical threshold in large parts of southern Finland, and possibly in parts of Central Finland, Pirkanmaa and South Savo.
While the north and east faced extreme heat, southern Finland experienced heavy thunderstorms on Saturday night and early Sunday morning. The strongest storm fronts moved across Kymenlaakso, Uusimaa and Kanta-Häme, with the heaviest activity centred in Virolahti and the Kymenlaakso coast.
A separate storm system developed overnight in Southwest Finland and the archipelago, with powerful cells moving from the Åland Islands towards the Swedish coast near Gävle.
Although thunderstorm activity weakened over the Gulf of Finland due to cold surface water, currently just 14–15°C, lightning and rain continued throughout the night along the coastal regions.
Further thunderstorms are expected to form over Latvia by midday Sunday, with the front likely to track across Estonia before reaching southern Finland by evening. Meteorologists forecast that the next storm system will move in via Porkkalanniemi towards southeast Finland.
A separate rain warning remains in effect for southern Finland, where downpours associated with thunderstorms could deliver more than 20 millimetres of rain per hour. FMI has warned that localised flooding is possible, particularly in urban areas.
According to FMI meteorologist Jaakko Savela, pinpointing the exact timing of storm formation remains difficult. While showers may occur during the day, evening hours are considered the most likely period for further storm development.
HT
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Source: www.helsinkitimes.fi
