Theoretical ice thickness information is calculated using average daily temperatures and snow depth on ice. The average daily temperature is subtracted from 32 degrees F to get freezing degree days, which are accumulated from the beginning of the ice season to get the freezing index that is used to calculate theoretical ice thickness. Another important consideration is the insulation provided by the snow on the ice, which acts to slow the rate of growth of the ice. The snow conductivity can vary greatly between 0.04 for freshly fallen snow and .2 for wind packed hardened snow. The hard packed snow has fewer air pockets and thus has poorer insulation capacity that is reflected by greater heat conductivity. The rate of heat loss that is conducted from the ice-water interface through the ice and snow to the cold air surface equates to the rate at which heat is released by the growing ice. Thus the rate of ice growth each day is calculated from the heat loss on that day.

The other impact that snowfall can have is that the weight of the snow can submerge the ice and allow water to flow through cracks in the ice and overflow onto the top of the ice surface and saturate the lower layers of the snow. This condition can be hazardous for any form of travel on the ice. The overflow eventually freezes and is called snow ice.