It is not inevitable that it will snow when the temperature drops to minus, but it is more likely to occur in cold temperatures. Snow is formed when the temperature is cold enough for water vapor to condense and freeze into ice crystals, which then fall to the ground. If the temperature is below freezing, it is more likely that the water vapor in the air will condense and freeze into snow. However, other factors, such as humidity and the presence of ice nucleators, also play a role in whether it will snow.
