July has been unusually cool in Finland, with highs barely reaching 20 degrees Celsius.

In June, the mercury hit 32 degrees Celsius in the northern city of Oulu, whereas July's highs have hovered around 20 degrees.

Yle meteorologist Joonas Koskela said recorded daytime temperatures of 10C in Kuhmo and Ilomantsi in eastern Finland on Friday are considered especially nippy for this time of year.

Air flows from the North Pole and Arctic Ocean are cooling down eastern Finland, according to Koskela. The rest of the country has also experienced chilly conditions, particularly at night.

"Last night there was frost in parts of western Finland and Lapland. That's not good for crops, especially strawberries," he said.

Finland should gradually warm up over the course of next week, though no radical change in conditions is expected.

While July, the most popular summer vacation month in Finland, has been unseasonably cool, June was warmer than average, with 11 days of temperatures in excess of 25 degrees Celsius, a uniquely Finnish threshold for describing weather as "hot".