From Tuesday, SMHI has issued a warning in the eastern part of Götaland and southeastern Svealand.
In the afternoons, the temperature is expected to reach 26 degrees or more.
The peak is reached on Wednesday and Thursday with 30-35 degrees, writes SMHI.
According to Petter Ljungman, the heat begins to become dangerous when you have lost too much fluid and salt.
In the worst case, the heat leads to a circulatory collapse.
Hear him tell more in the clip above.
Heat record in Europe
In the last ten days, the heat has hit hard, especially in Spain and Portugal.
Last week, a new heat record was set for July in Portugal with 47 degrees, before slightly cooler weather pulled in on Monday.
Temperatures are also expected to rise in France, Germany and the United Kingdom.
In Nantes in western France, a new heat record was set at 42 degrees on Monday.
At Luton Airport north of London, the heat has led to damage to the runway, which has stopped air traffic.
Some schools have been closed at the same time as train operators advise against unnecessary travel.