Weather
Arizona Winter Weather: How 1 Inch of Water Can Become 20 of Snow
Flagstaff, AZ – Winter storms across Arizona can produce dramatically different snowfall totals, even when communities receive similar amounts of moisture. From Flagstaff to Prescott, just 1 inch of l
By Cole Barrett · 2026-11-10T08:03:08.312Z
Flagstaff, AZ – Winter storms across Arizona can produce dramatically different snowfall totals, even when communities receive similar amounts of moisture. From Flagstaff to Prescott, 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 can vary considerably.
Heavy, wet snow may have a ratio near 5 to 1, producing approximately 5 inches from 1 inch of liquid precipitation.
Under atmospheric conditions favorable for fluffy snow, ratios can sometimes reach 20 to 1, producing approximately 20 inches from the same moisture.
These ratios describe possible snow densities, not an approaching storm.
Flagstaff and Prescott: Why Snowfall Can Differ
Flagstaff sits at approximately 7,000 feet above sea level near the San Francisco Peaks, making it one of Arizona's snowier cities.
Prescott, at roughly 5,300 feet, experiences a somewhat milder winter climate because of its lower elevation.
During some winter storms, Flagstaff may receive substantial snowfall while Prescott experiences lighter accumulations or mixed precipitation.
Arizona's mountainous terrain adds another important factor.
When moist air rises over higher elevations, it cools and can produce additional precipitation through a process known as orographic lift.
Meanwhile, lower desert cities such as Phoenix and Tucson generally experience warmer conditions that make accumulating snow much less common.
What Arizona Residents Should Know
Heavy, wet snow can weigh down trees and power lines, increasing the potential for damage and outages.
Lighter snow can accumulate more deeply and create visibility problems when strong winds develop.
Travel conditions can change quickly along Interstate 17, Interstate 40 and State Route 89A, particularly where highways climb into higher elevations.
Snowmelt followed by overnight freezing can also create hazardous icy roads.
Understanding snow to liquid ratios helps explain why snowfall estimates can change even when expected moisture amounts remain similar.
For Arizona residents, snowfall depth depends on more than precipitation alone. Elevation, temperature, mountain terrain and wind all influence final accumulation totals.