"We have a challenging day ahead of us," said the Swedish Transport Administration's press communicator Peter Jonsson.
The heat wave with temperatures up to 30 degrees in large parts of Sweden is primarily affecting rail traffic, where the heat is causing problems with fires and 'sun curves,' a phenomenon where the heat of the sun bends tracks.
On Wednesday, traffic on the important western main line had to be suspended for a short time due to a fire in the track area in Hallsberg. The risk of sun curves is mainly on the smaller lines.
"We have not closed any lines due to the heat. What we have done is that we have reduced the speed. Then it may still be the case that the train companies themselves choose to cancel traffic," said Jonsson.
Further cases of bleeding asphalt on roads, where the binder that holds the asphalt together softens and expands, have been reported from Västernorrland.
Jonsson describes the situation as challenging.
"We have a good preparedness. The challenge is that we cannot know exactly where things will happen. It's not like windy weather over the west coast that moves in. Then you know where it will happen. This can happen over large areas, so we must have a high level of preparedness in all regions."
Significantly cooler weather is expected across the country this weekend, with rain and wind in southern parts of Sweden.