It can get as hot as 35 degrees in some places in Örebro County on Wednesday and Thursday.
An "orange" warning is issued for the southern parts of the county and a "yellow" for the entire county.
The high temperatures can put increased strain on the body, which can create problems, especially for risk groups.
On Thursday, the heat is expected to culminate.
According to SMHI's weather forecast, the temperature will drop to 22 degrees on Friday in Örebro.