A tropical night was also recorded in many places, with 42 different weather stations registering a temperature above 20 degrees Celsius throughout the night.
Charged clouds moved north past Stockholm early on Sunday morning, the Swedish Meteorological and Hydrological Institute (SMHI) said.
“It is an estimated figure, but I would place it at between 5,000 and 10,000 flashes of lightning from midnight onwards. There was a lot over Stockholm during the early morning,” SMHI’s duty meteorologist Jon Jörpelund said.
Thunderstorms were forecast to move north towards Gävleborg and Dalarna before later reaching Härjedalen and Jämtland by late afternoon or evening. The storms began on Saturday afternoon, with 6,000 lightning bolts registered.
“There will definitely be more flashes today than yesterday. Particularly if lightning storms begin again this afternoon,” Jörpelund said.
Saturday night again saw warm temperatures in many parts of Sweden.
“Forty-two stations recorded a tropical night. I don’t know if that’s a record, but I have not experienced such a high number before. It has been very widespread, including inland,” the meteorologist said.
A tropical night is defined as a 24-hour period in which the temperature does not fall below 20 degrees Celsius.
Although 18 stations recorded such conditions in a single night earlier in July, Saturday’s figure is considered to be unusually high.
“It happens on the coasts but there were also tropical nights in inland areas. Karlstad, Arvika, Mora, Västerås, Sala and Norrköping all had tropical nights, for example,” Jörpelund said.
A dip in temperature was forecast for Sunday, but heat in excess of 30 degrees Celsius is expected to return on Monday and Tuesday.