The search for the missing men was called off on Friday afternoon due to stormy weather. One of the men is in his twenties, the other in his sixties.
“The chances that either of them are still alive are not great,” police spokesman Per Strömbäck told the TT news agency.
A total of four forestry workers from the Örebro area were aboard the boat when the accident took place at Lövudden outside Västerås.
Two men in their twenties were rescued from the water and taken to hospital in Västerås, where they are being treated for hypothermia.
“Their lives are not in any danger,” said Strömbäck.
A large search party, including helicopters, divers and rescue boats was sent out to look for the men but adverse weather conditions led to the postponement of the search at 1.30pm. According to a statement from rescue officials, visibility on Lake Mälaren was poor, with strong winds and choppy waters.
None of the men were wearing life jackets, according to police. The search for the two men is set to resume at 9am on Saturday.