Several hundred firefighter units were dispatched to over 500 locations across the country to pump water from houses, patch up roofs, divert torrents and clear fallen trees and debris from roads, the Civil Protection and Disaster Relief Administration said.
The biggest damage was sustained by the area of Domžale about 15 kilometres north-east of Ljubljana, which was battered by hail the size of an egg for more than half an hour. Other parts of the country experienced landslides and flooding and power outages.
The state of the damage in Domžale was inspected on the ground by Economy Minister Zdravko Počivalšek, who said more than 390 buildings had been damaged there. Deputy Mayor Renata Kosec put the damage estimate at around EUR 2.5 million.
The hail damaged so many cars that some repair shops there have run out of spare windshields.
The Civil Protection and Disaster Relief Administration received "an unbelievable 851 calls for help" between 9pm and 11pm from the Domžale area, a municipality with a population of 13,000.
Only there, 300 firefighters helped out locals throughout the night plus civil protection unit members, deputy civil protection chief Peter Gubanc said.
Teams continued their work during the day to tackle the worst damaged buildings, along with insurance agents who were busy assessing the damage throughout the country.
In and around Domžale, most damage was done to roofs and cars, while hail was reported to have destroyed this year's crops in some parts of Koroška in the north of the country.
In Prevalje, a municipality with a population of less than 7,000, the damage has initially been estimated at more than EUR 300,000 with many roads blocked by landslides or fallen trees and some public buildings flooded.
Prevalje Mayor Matic Tasič said it would cost between one and two million euro to repair the damage by what was the third such extreme weather occurrence in just two weeks.
Zasavje in central Slovenia also had to cope with impassable roads and flooded buildings and Laško to the north-east was also hit by hail. Much of the village of Rečica there is under the water and tap water in Žalec is no longer fit for drinking.
Sections of roads were carried away by torrential water, a group of scouts had to be evacuated after being flooded and a home in Slatina pri Ponikva caught on fire after being struck by lightning.
Several locations were also flooded in Velenje and Polzela.
Počivalšek will notify the government of the state on the ground and they will examine how the government can help and tackle the damage as soon as possible.