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Maine Snow: Why 1 Inch of Rain Means 20 of Snow in Portland, Bangor
Portland, ME – As Maine heads deeper into winter, residents from Portland to Bangor may notice something surprising about snowfall forecasts: The same amount of moisture can produce dramatically diffe
By Sophie Caldwell · 2026-11-10T07:31:09.653Z
Portland, ME – As Maine heads deeper into winter, residents from Portland to Bangor may notice something surprising about snowfall forecasts: The same amount of moisture can produce dramatically different snow totals. Under certain atmospheric conditions, just 1 inch of liquid precipitation can translate into 20 inches of snow.
The difference comes down to a measurement known as the snow to liquid ratio, which helps meteorologists estimate how much snow will accumulate during winter storms.
Why One Inch Can Become 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, that ratio can change significantly depending on atmospheric conditions.
Heavy, wet snow may have a ratio near 5 to 1, producing roughly 5 inches of snow from 1 inch of liquid precipitation.
Colder, fluffier snow can sometimes reach a 20 to 1 ratio, producing approximately 20 inches from the same amount of moisture.
Portland and Bangor Could Experience Different Results
Portland's coastal location exposes it to relatively warmer Atlantic air, which can contribute to wetter, denser snowfall during certain storms.
Bangor, farther inland, can experience colder atmospheric conditions that sometimes favor lighter, fluffier snow.
However, temperature is not the only factor.
Wind can break apart delicate snowflakes, while moisture and ice formation inside clouds influence snowflake structure and density.
Why This Matters for Maine Residents
Wet snow can place greater weight on tree branches and power lines, potentially increasing the risk of damage.
Fluffier snow may accumulate more deeply while containing less water per inch.
These differences also affect shoveling, snow removal and road conditions.
Understanding snow ratios helps explain why snowfall predictions can change even when the expected amount of precipitation remains similar.
For Maine residents, the amount of moisture in a winter storm is only part of the story. How that moisture freezes and reaches the ground can make a major difference in the final snowfall total.