39°C?, that's really hot. Our Summers average at 15°C (59F). The hottest Summer days can sometimes be over 30°C (86F), and the coldest about 10°C (50F). Depending on your location in Finland, the lowest temperature in Summer can even go below 0°C.
The termic Summer in Finland is when the average temperature stays above 10°C.
My figures may be quite off. Wikipedia may have somewhat more accurate statistics.
Well 39°C is not consider hot at my part of the world. The temperature touches 48 °C to 49°C during extreme summer season. Lowest temperature in summer below zero degree is simply amazing @gamer00