Cyclist Ruben Venuti, 31, died of a heart attack following a mountain climb in the region of Friuli-Venezia Giulia, Il Gazzettino reported.
Two men also died in the neighbouring Veneto region. Dino Bez, 57, collapsed outside the Longarone train station, while 50-year-old Massimo Roccatello suffered a heart attack in front of colleagues, the newspaper said.
Italy's heatwave hotline has received 3,000 calls since the heatwave began on July 26th. The majority of the callers were aged between 19 and 64, the Ministry of Health said on Monday.
Meanwhile, an 80-year-old bishop was saved from the heat by a resourceful member of the community. Flavio Carraro was leading a procession when he took a turn for the worse in the heat. A woman quickly brought him wine and he immediately recovered, Il Gazzettino reported.
The Ministry of Health has issued level three warnings across the country and particularly in the north east. This indicates that the heatwave will have a negative impact on people who are usually healthy, and not only on high-risk groups such as children and the elderly.
The temperature is set to reach record highs of up to 42C on Wednesday and Thursday, before thunderstorms sweep across the north and bring temperatures down by 5-8C, Il Messaggero reported.