A 16-year-old girl on a camping trip was among two people who died after violent storms hit northern Italy, Prime Minister Giorgia Meloni said, while in the south wildfires forced the temporary closure of Sicily's Palermo airport.
The teenager was killed when a tree fell on her tent during a scout camp near Brescia, after high winds and torrential rain overnight.
Yesterday, a woman died after also being hit by a falling tree in Lissone, north of Milan.
Ms Meloni confirmed the two "tragic" deaths due to bad weather, and offered her thoughts to their loved ones on social media.
Milan residents reported torrential rain and hail in the early hours of this morning, which flooded streets and uprooted trees, many of which fell onto parked cars.
Transport authorities reported serious damage to the city's electricity network, while an AFP journalist said water in the historic centre was temporarily shut off.
Firefighters said the situation was "very serious", reporting more than 200 calls for help across Milan since 4am local time.
But even as the north was drenched, the heatwave across the south persisted, with temperatures of 47.6 degrees Celsius recorded in the eastern Sicilian city of Catania.
Firefighters on the island spent a night battling wildfires, one of which approached so close to Palermo airport that it shut down for several hours this morning.
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Italy's Civil Protection Department reported "extensive fires" across the south, saying air support had been requested for nine incidents in Sicily, nine in Calabria and another in Sardinia.
"We are experiencing in Italy one of the most complicated days in recent decades - rainstorms, tornadoes and giant hail in the north, and scorching heat and devastating fires in the centre and south," said Civil Protection Minister Nello Musumeci.
Writing on Facebook, he added: "The climate upheaval that has hit our country demands of us all... a change of attitude."
Palermo airport operator said in a tweet shortly before 10am that only a limited number of outbound flights would be allowed "for the moment".
However, it later added that a plane from Turin in northern Italy had been able to land.
The airport was closed earlier as firefighters sought to put out a major blaze in a nearby area that also disrupted local road and rail traffic.
Regional authorities said a woman died after an ambulance could not reach her home due to the blaze.
The temporary closure of the airport added to Sicily's travel misery at the peak of the tourist season.
The island's main airport of Catania, Italy's fifth-biggest, was closed last week due to a fire in a terminal building and has reopened only for a few flights.
A heatwave has hit southern Europe, with scorching temperatures bringing increased risk of fires and deaths.
In some parts of eastern Sicily, temperatures rose to 47.6C yesterday, close to a record European high of 48.8C recorded on the island two years ago.
Today, Italy put 16 cities on red alert because of the high temperatures.
These include Palermo and Catania, where power and water supply cuts that local officials blamed in part on the heat have been frequent in recent days.
