June, July and August saw record highs at nearly all weather stations in the country's most northern areas.

The heat was caused by a high pressure system combined with climate change, the institute said.

High temperatures set off droughts and extensive wildfires across the Scandinavian country.

"The summer in Lapland in Finland was clearly the warmest on record," Mika Rantanen, a climate change researcher at Finland's Meteorological Institute, told AFP.

The average temperature from June to August was 16.2 degrees Celsius (61 degrees Fahrenheit) for Finland as a whole, matching the record hot year of 1937.

In Sodankyla -- a small town north of the Arctic Circle -- the average temperature was 15.9 degrees Celsius -- around 1.8 degrees Celsius warmer than what it would have been without the effects of climate change, according to the weather agency.

"Northern Norway, northern Sweden and even (the) Svalbard (archipelago) also had their warmest summer on record," Rantanen added.

The record high temperatures measured in Lapland exceeded the averages recorded since the beginning of the 20th century by 2 to 3.5 degrees Celsius.

"The minimum temperatures were very high in Lapland... there were no cold spells at all," Rantanen added.

The Arctic has been warming almost four times faster than the rest of the world since 1979, according to Finnish and Norwegian researchers.

Very warm summers of this kind were now approximately 70 times more likely to occur due to climate change than they were at the beginning of the 20th century, Finnish climate experts estimate.

"In the beginning of the 20th century the probability of such warm summers was once every 2,000 years. But in the current climate the likelihood is once every 25 years," Rantanen said.

"If you extrapolate this into the future, it means that in the year 2050 these kind of warm summers will occur every five years," he said.