Rain to Snow
Convert rainfall to snowfall and vice versa using temperature-based snow coefficients. Free online weather calculator with instant results, charts, and breakdowns.
Snow coefficient: 10 (27 to 34 °F (-3 to 1 °C))
1 inch of rain = 10 inches of snow at this temperature
About This Calculator
The Rain to Snow Calculator converts between rainfall and snowfall amounts based on temperature-dependent snow coefficients. Whether you are a meteorology student, a weather enthusiast, or just curious about how much snow a rainy day would have produced, this tool gives you instant answers with clear visual breakdowns.
The conversion uses the formula Snow = Rain × Snow Coefficient. The snow coefficient varies with temperature from 0.1 at 34-45 °F (barely any snow) to 100 below -20 °F (very dry powdery snow). At typical freezing temperatures around 27-34 °F, the standard 1:10 ratio applies where 1 inch of rain equals 10 inches of snow. You can also convert snow back to rain to determine the liquid water equivalent of accumulated snowfall.
How the Snow Coefficient Works
The snow coefficient represents how many inches of snow are produced from 1 inch of liquid precipitation. Warmer snow near freezing is wet and dense (coefficient 10-15), while cold snow is light and fluffy (coefficient 40-100). The coefficient depends primarily on temperature but is also affected by humidity and wind conditions during snowfall.
Regional Notes
United States: This calculator uses inches, the standard US precipitation unit. The National Weather Service uses similar temperature-based snow-to-liquid ratios operationally.
United Kingdom: The same conversion principles apply, though precipitation is often measured in millimeters. The snow coefficient ratios remain the same regardless of unit system.
India: Snowfall is common in the Himalayan regions of Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, and Arunachal Pradesh. The Indian Meteorological Department uses snow-to-liquid ratios for hydrological forecasting in these regions.
Note: This calculator provides estimates based on temperature. Actual precipitation type and amount depend on many atmospheric factors including humidity, wind, and atmospheric lift.
Frequently Asked Questions
How do you convert rain to snow?
To convert rain to snow, multiply the rainfall amount in inches by the snow coefficient for the temperature. For example, at 27-34 °F the coefficient is 10, so 1 inch of rain equals 10 inches of snow. The formula is Snow = Rain × Snow Coefficient.
How many inches of snow equals one inch of rain?
On average, 1 inch of rain equals about 10 inches of snow. However, this varies with temperature: wet snow at 34 °F may give a 1:10 ratio while dry powdery snow below -20 °F can reach ratios of 1:100 or more.
At what temperature does rain turn to snow?
Rain turns to snow when the atmospheric temperature is at or below 32 °F (0 °C). Snowflakes form in cold clouds and if the ground temperature is also below freezing, they reach the ground as snow rather than melting into rain.
What is the snow coefficient?
The snow coefficient is the number of inches of snow produced by 1 inch of rainfall at a given temperature. Common values are 10 at 27-34 °F, 15 at 20-27 °F, 20 at 15-19 °F, 30 at 10-14 °F, 40 at 0-9 °F, 50 at -20 to -1 °F, and 100 below -20 °F.
Can I calculate how much water is in snow?
Yes, use the snow-to-rain direction in this calculator. Divide the snowfall depth in inches by the snow coefficient to get the equivalent rainfall in inches. For example, 20 inches of snow at 15-19 °F (coefficient 20) equals 1 inch of rain.
Why does the rain to snow ratio vary?
The ratio varies because temperature, humidity, wind, and atmospheric lift all affect snowflake structure. Warmer temperatures produce wet, dense snow with a lower ratio (1:10), while very cold temperatures produce light, fluffy snow with a higher ratio (up to 1:100).
Is the rain to snow calculator free?
Yes, this rain to snow calculator is completely free to use with no registration or hidden charges. You can bookmark or share your calculation results via URL.
How do weather services determine rain vs snow forecasts?
Weather services use atmospheric temperature profiles, wet-bulb temperatures, and precipitation type models. If the entire atmospheric column is below freezing, snow is expected. A warm layer aloft can cause rain even when surface temperatures are near freezing.