Passengers on a craft forced to land in the water at Drevviken were quickly rescued by a boat and taken to safety.
Two balloons crash landed at Kärrtorp playing fields in southern Stockholm.
“Eight of our passengers were injured at Kärrtorp. One of them broke a leg,” said Casbar Andersson, head of operations at Ballongflyg Upp och Ner.
Six of Andersson’s balloon’s were hit by the storm, which arrived without any prior warning from Sweden’s largest meteorological agency.
“It is very regrettable that SMHI, which is the service we use, was not able to forecast the sudden storm. But mainly I’m relieved that it didn’t turn out worse considering the weather and the number of people in the air,” he said.
A day of tropical heat was followed at 9.40pm by torrential rain, which soon began to weigh down the balloons.
Stefan Danielsson was among eleven people on board a hot air balloon that struck the top of a hill as part of its forced decent at Högdalen in the south of the city.
“In the back of my mind I thought this is going to end really badly because it went so incredibly fast. Deep inside I was counting down my final seconds,” he said.