Weather experts said the heatwave, called Caronte, will continue over the next week before subsiding towards the end of the month.
The endless heat looks as if it will propel July 2015 into the record books as the hottest month ever.
"Considering it's only July, and not in the summer in its entirety, it is the most intense heat wave in 70 years," Edoardo Ferrara, a meteorologist with 3bmeteo.com, said on Friday.
Temperatures will peak at 40 degrees Celsius in parts of Italy, before cooling off towards the end of the month, bringing potential thunderstorms to the north and central Italy.
Forecast temperatures for 12pm on Monday. Source: meteo.it
Over 100 people have died of the heat since the start of the month, with Arpa Piedmont saying on Friday that the heatwave had claimed the lives of 140 pensioners in the region alone. Other lives have been claimed in Liguria, Tuscany and Sardinia.
Current hot temperatures are reminiscent of the summer of 2003, when the whole of Europe was gripped by a heatwave that killed 18,000 people in Italy alone.
The current heatwave has caused the number of calls to the emergency services in Italy to spike by around 10 percent.