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Iowa Winter Weather: How 1 Inch of Water Can Become 20 Inches of Snow
Des Moines, IA – Winter storms across Iowa can produce dramatically different snowfall totals, even when communities receive nearly identical amounts of moisture. From Des Moines to Cedar Rapids, just
By Nolan Pierce · 2026-11-10T07:50:37.124Z
Des Moines, IA – Winter storms across Iowa can produce dramatically different snowfall totals, even when communities receive nearly identical amounts of moisture. From Des Moines to Cedar Rapids, just 1 inch of liquid precipitation can sometimes produce 5 inches of heavy, wet snow or as much as 20 inches of lighter, fluffier snow.
The difference comes down to the snow to liquid ratio, which measures how much snow accumulates from a given amount of liquid water.
Why One Inch Can Produce 20 Inches of Snow
A commonly used forecasting guideline is the 10 to 1 ratio, meaning 1 inch of liquid water produces approximately 10 inches of snow.
However, actual snowfall ratios vary considerably.
Heavy, wet snow may have a ratio near 5 to 1, producing approximately 5 inches from 1 inch of liquid precipitation.
Under colder atmospheric conditions favorable for fluffy snow, ratios can sometimes reach 20 to 1, producing approximately 20 inches from the same moisture.
Iowa's cold winters can support higher snowfall ratios, although extremely cold temperatures do not automatically guarantee fluffier snow.
Des Moines and Cedar Rapids: Why Snowfall Can Differ
Des Moines, located in central Iowa, frequently experiences winter storms moving across the Great Plains and Midwest.
Cedar Rapids, farther east, can encounter different temperatures and precipitation amounts depending on a storm's track.
A slight shift in a winter storm's path can determine which communities receive heavier snow and which experience lighter accumulation.
Cold Arctic air moving south from Canada can also influence snow density and precipitation type.
Across Iowa's open agricultural landscape, strong winds can create blowing and drifting snow, making measured snow depth vary considerably even within the same community.
What Iowa Residents Should Know
Heavy, wet snow can weigh down trees and power lines, increasing the potential for damage and outages.
Lighter, fluffier snow can be especially vulnerable to strong winds, producing dangerous visibility reductions and significant drifting.
Travel conditions can deteriorate rapidly along Interstate 35, Interstate 80 and Interstate 380, particularly during blowing snow.
Understanding snow to liquid ratios helps explain why snowfall forecasts can change even when expected precipitation amounts remain similar.
For Iowa residents, winter storm impacts depend on more than snowfall depth. Temperature, wind speed, storm tracks and snow density all influence accumulation and travel hazards.