Heavy showers may produce large amounts of rain in a short time and cause flooding on Saturday in Västra Götaland County and parts of Jönköping, Örebro and Värmland counties.
"Locally, between 30 and 60 millimetres of rain can fall in a short time," said Fanny Saarela, on-duty meteorologist at SMHI.
"It is a low pressure system that is coming in, and at the same time, it has brought down colder air. So these rain showers will probably be heavy," said Saarela.
The rain will start to move in at 10am on Saturday morning and the warning is in place until 10pm. This means a major change in the weather after last week's heatwave, when temperatures reached 30 degrees.
"It will be very noticeable in the temperature," said Saarela. "On Saturday in this area we may still reach 20 degrees locally, but otherwise [it will be] between 15 and 20. On Sunday we will have to settle for 15 degrees."
Because the land is dry due to the hot weather over the past week, the risk of flooding is reduced.
"It's quite dry, so the land should be good at absorbing the rain. But in cities, on hard surfaces, there can be flooding on roads, viaducts and so on," said Saarela.
Cooler temperatures are expected to persist.
"I don't see a return to this hot weather that we've had now," Saarela said.
In the far north there could even be snow on Saturday.
"On the highest peaks in the mountains there could be some patches of snow."