The temperature rose to 18 degrees Celsius at about 2 pm on Wednesday at the weather station in southern Finland's municipality of Vihti.
According to the Finnish Meteorological Institute's meteorologist Jaakko Savela, the reading marked the earliest time of the year when the temperature was that high in Finland, according to record books.
"You can't blame climate change for [causing] the temperature of a single day. These temperatures are caused by weather conditions," Savela said, while acknowledging that such high temperatures are exceptional for this time of year.
Thursday is also expected to be similarly warm in Southern Finland. However, people up north will start to see signs of a chillier turn in the weather.
According to Yle meteorologist Aleksi Lohtander, temperatures across the country are expected to become a lot more winter-like by the end of the week
On Saturday, temperatures will only reach a couple of degrees above zero. Daytime local snow showers are also possible, but skies are expected to clear up at night.
In Lapland, the returning cold snap will bring temperatures down to below freezing, according to Lohtander.