Nordic Countries Bake in Unprecedented and Prolonged Summer Heat Not Seen in Decades

Temperatures surpassed 30C in parts of Finland, Norway and Sweden, which is significantly higher than average summer temperatures in Nordic countries.

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Northern European countries are experiencing an unprecedented heatwave, with temperatures breaking records in Finland, Norway, and Sweden. 

Finland is enduring its most severe and prolonged heatwave on record. Temperatures exceeded 30C for 22 consecutive days until last Saturday, reaching 30.4C in the municipality of Ranua, in the northernmost region of Lapland and on Hailuoto Island in the northern Baltic Sea, according to the Finnish Meteorological Institute (FMI).

Finland’s global warming rate is higher than the global average. “It has long been known that the higher latitudes we are, the faster the temperatures rise,” explained Pauli Jokinen, an FMI meteorologist. In 2024, the country’s average temperature was 3.4C above pre-industrial levels.

Finland’s accelerated warming indeed stems from its Arctic proximity, where melting snow and ice have intensified temperature increases, explained FMI’s Director General Petteri Taalas. 

Meanwhile in Norway, several areas in the North Trøndelag county saw temperatures exceed 30C for 13 days in July – unusually high for the country, where summer temperature averages are usually around 13-18C. The Norwegian Meteorological Office confirmed Norway’s hottest day so far this year on July 16, with Meråker in north-central Norway, close to the Swedish border, reaching 34C. 

“Global warming isn’t going away, …and it will get stronger in the decades ahead, so the summer of 2025 is a clear illustration of how things will be,” said Bjørn Samset, a researcher at the Norwegian climate research institution Cicero.

In Sweden, the municipalities of Haparanda and Jokkmokk, last month saw heatwave conditions for 14 and 15 consecutive days, respectively. Heatwaves this long have not been recorded there in more than 100 years. 

Heat conditions persisted through August. On Friday, Pajala in northern Sweden had its warmest day on record, with the mercury reaching 29.6C.

“What stands out is that it has been so long-lasting in the north and the tropical nights,” said Charlotta Eriksson, a meteorologist at the Swedish Meteorological and Hydrological Institute. 

July was also Iceland’s warmest on record, equaling 1933. 

On July 14, 70% of weather stations recorded temperatures above 20C, with Hjarðarland in the Southwest reaching a high of 29.5C, the highest temperature since 2008. Iceland’s average July temperature ranges between 10-15C, occasionally reaching 20-25C. 

“Such jumps in temperature records are highly unusual and demonstrate just how warm it was today,” said Kristín Hermannsdóttir, Head of Weather Services at the Icelandic Meteorological Office.

“As climate change progresses, exceptionally severe heatwaves will intensify,” said Heikki Tuomenvirta, a scientist at the Finnish Meteorological Institute. “They are occurring more frequently, are more severe and last longer.”

The unusually hot weather is caused by a slow-moving high-pressure system stuck over northern Europe, known as the heat dome. 

When warmer surface air attempts to rise but is forced downward by the overlying high-pressure system, it sinks and compresses again, further reheating the air. This mixes with trapped surface heat, intensifying the process. This creates a self-sustaining cycle: sinking air heats and dries the atmosphere, allowing more solar energy to heat it, which drives further upward attempts and subsequent compression, trapping increasing amounts of heat in a giant dome-like pattern. 

“This dome acts like a lid, preventing heat from escaping and blocking cloud formation, which leads to persistently high temperatures and minimal relief from the heat,” said Brandon Buckingham, meteorologist for the American private media company AccuWeather, which provides commercial weather forecasting services.