Players took to the pitch for a warm-up in northern Italy but huge puddles had formed and the surface was deemed unplayable by the match referee and the two captains.
"The match has been postponed due to a waterlogged pitch," league officials said confirming the game had been pushed back a day to Tuesday at 19:45 CET.
Europa League champions and fourth in Serie A last season, Atalanta have had a mixed start to the season with two wins and two defeats in the league. The Bergamo side were held to a goalless draw at home against Arsenal in their Champions League opener last week.
A win for Atalanta would put them level on points with fourth-placed Juventus, while promoted Como are struggling second from bottom.