They named the Italians as Claudio Alonzi, 62, and Tiziana Barnobi, 53. The Israeli was identified as Shimoni Erez, 50.
Anya Bozhkova, the 50-year-old Russian wife of the boat’s captain, also died.
The vessel with more than 20 tourists and crew sank in strong winds.
According to Italian news outlets, the boat had been carrying about 25 people who were celebrating a birthday when a storm developed over the lake, later turning into a “small hurricane”.
The 16m (52ft) long boat capsized and sank on Sunday evening between the towns of Sesto Calende and Arona.
Everyone onboard went into the water, but many of the passengers swam ashore or were rescued by other boats.
Rescue divers and a helicopter scrambled to help with the search at the lake’s southern end, and several ambulances and an air ambulance attended the scene.
A video shared by firefighters showed chairs and other debris floating in choppy waters.
Five people were taken to hospital.
Lake Maggiore – on the south side of the Alps – is shared by Italy and Switzerland and is a popular destination for tourists.
The area has recently seen poor weather, with Italy’s meteorological service issuing thunderstorm warnings.
