June and July have seen record average temperatures recorded at almost all measuring stations in Finland.
Yle gathered the figures for a representative sample of Finnish Meteorological Institute's stations, and found that this summer's averages were, at many places, the highest on record.
In all, Yle compared data from 1,338 summers at 20 different measuring stations, chosen for a geographical spread throughout the country and reliable data stretching back decades.
For example Helsinki's Kaisaniemi station has measured temperatures since 1882, and Sodankylä's Tähtelä has done the same since 1908.
The average daily temperature for the period between 1 June and 21 July has never been as high as it was in 2021 at either station.
Rovaniemi airport and Utsjoki's Kevo station recorded a higher average in 1972, but they were the only places not to have a record summer.
Long heatwave in Anjala
This summer has also seen the longest spell of 'hot' weather (defined in Finland as a temperature over 25 degrees Celsius).
Anjala measuring station in Kouvola breached that 'helle' limit every day between 18 June and 18 July, giving a 31-day streak that beat the previous record by five days.
The hotter spell of weather is down to a high pressure system that has remained in place over Finland for an extended period.
Meteorologist Ville Siiskonen says there could be many factors behind the heatwave, with the whole northern hemisphere analysed after the fact to decipher what has happened.
One factor is known, however: climate change. Because of the heating climate, each heatwave is a little hotter than it would have been 30 years ago, even if similar conditions would also have created a heatwave back then..
"There are indications that climate change could make it more likely that weather systems get 'stuck'," said professor Hannele Korhonen of the Meteorological Institute. "But we do not know enough about this from a scientific perspective."
Korhonen says that this is not the 'new normal' for Finland — yet. That depends on how quickly greenhouse gases are reduced in the coming decades.