As the weather charts, also the meteograms provided by saakeskus.fi are based on data of the GFS model of the US National Oceanic and Atmospheric Administration / National Centers for Environmental Prediction.
Please keep in mind that computer models are not always precise and the further you go to the future, the more likely is a difference between the model and what really will happen.

The windchill temperature is calculated according to the new windchill index formula from 2001.

Please note also that all date and time information are in Zulu-time which is UTC or GMT. For Finland please add 2 hours in winter and 3 hours in summer.