Inch of Rain to Snow Converter
Calculate snowfall depth from rainfall based on temperature conditions
Quick Conversions
Rain to Snow Ratio Chart
The amount of snowfall produced by rainfall varies significantly with temperature. Colder temperatures create lighter, fluffier snow with higher ratios, while warmer temperatures near freezing produce denser, wetter snow.
| Temperature (°F) | Temperature (°C) | Snow Ratio | 1 Inch Rain = | Snow Type |
|---|---|---|---|---|
| 34 to 45 °F | 1 to 7 °C | 1:10 | 10 inches snow | Wet, heavy |
| 27 to 34 °F | -3 to 1 °C | 1:10 | 10 inches snow | Average density |
| 20 to 27 °F | -6 to -3 °C | 1:15 | 15 inches snow | Light, fluffy |
| 15 to 19 °F | -9 to -7 °C | 1:20 | 20 inches snow | Powder |
| 10 to 14 °F | -12 to -10 °C | 1:30 | 30 inches snow | Very light powder |
| 0 to 9 °F | -18 to -13 °C | 1:40 | 40 inches snow | Dry powder |
| -20 to -1 °F | -29 to -18 °C | 1:50 | 50 inches snow | Extremely dry |
| < -20 °F | < -29 °C | 1:100 | 100 inches snow | Ultra-fine powder |
How to Convert Rain to Snow
Converting rainfall to snowfall requires knowing the temperature during precipitation. Follow these straightforward steps to calculate expected snowfall.
Step-by-Step Calculation
- Determine the amount of rainfall in inches
- Check the temperature during the precipitation event
- Find the corresponding snow ratio from the chart above
- Multiply rainfall by the snow ratio to get snowfall depth
Example 1: Moderate Cold Conditions
Given: 2.5 inches of rain at 12 °F
Solution: At 12 °F (between 10-14 °F), the snow ratio is 1:30
Calculation: 2.5 inches × 30 = 75 inches of snow
Result: 2.5 inches of rain would produce 75 inches of snowfall
Example 2: Near Freezing Temperature
Given: 1 inch of rain at 32 °F
Solution: At 32 °F (between 27-34 °F), the snow ratio is 1:10
Calculation: 1 inch × 10 = 10 inches of snow
Result: 1 inch of rain produces 10 inches of snow
Example 3: Very Cold Conditions
Given: 0.5 inches of rain at -5 °F
Solution: At -5 °F (between -20 to -1 °F), the snow ratio is 1:50
Calculation: 0.5 inches × 50 = 25 inches of snow
Result: Half an inch of rain creates 25 inches of snow
Reverse Calculation: Snow to Rain
To convert snowfall back to rainfall equivalent, divide the snow depth by the snow ratio.
Example: Converting Snow to Rain
Given: 12 inches of snow at 16 °F
Solution: At 16 °F (between 15-19 °F), the snow ratio is 1:20
Calculation: 12 inches ÷ 20 = 0.6 inches of rain
Result: 12 inches of snow equals 0.6 inches of rainfall
Popular Rain to Snow Conversions
Here are commonly searched rainfall amounts and their snow equivalents at different temperatures.
Half Inch of Rain
At 30°F: 5 inches of snow 1:10
At 20°F: 7.5 inches of snow 1:15
One Inch of Rain
At 30°F: 10 inches of snow 1:10
At 15°F: 20 inches of snow 1:20
Two Inches of Rain
At 25°F: 30 inches of snow 1:15
At 12°F: 60 inches of snow 1:30
Three Inches of Rain
At 30°F: 30 inches of snow 1:10
At 5°F: 120 inches of snow 1:40
Typical Snowfall Scenarios
| Rainfall | Temperature | Snowfall | Description |
|---|---|---|---|
| 0.1 inches | 30 °F | 1 inch | Light dusting |
| 0.25 inches | 25 °F | 3.75 inches | Light accumulation |
| 0.5 inches | 20 °F | 7.5 inches | Moderate snowfall |
| 1 inch | 30 °F | 10 inches | Significant snow event |
| 1.5 inches | 15 °F | 30 inches | Heavy snowstorm |
| 2 inches | 10 °F | 60 inches | Major winter storm |
Factors Affecting Rain to Snow Conversion
Multiple atmospheric conditions influence how much snow forms from a given amount of rainfall.
Temperature
Temperature is the primary factor determining snow ratio. As temperature decreases, snow crystals become lighter and more intricate, resulting in higher snow-to-rain ratios. At temperatures just below freezing (32°F), snow is wet and dense with a 1:10 ratio. At temperatures below 0°F, snow becomes extremely light and fluffy, with ratios reaching 1:40 or higher.
Humidity Levels
Atmospheric humidity affects snow crystal formation. Drier air produces lighter, fluffier snow crystals because there’s less moisture to create dense snowflakes. Higher humidity creates wetter, heavier snow that compacts more readily.
Atmospheric Pressure
Pressure patterns influence precipitation intensity and snow crystal structure. Low-pressure systems often bring sustained snowfall with consistent ratios, while high-pressure conditions may produce lighter, drier snow.
Wind Conditions
Wind affects snow density through compaction and drift formation. Strong winds compress falling snow, reducing its measured depth and effectively lowering the snow-to-rain ratio. Calm conditions allow snow to accumulate without compression, maintaining higher ratios.
Elevation
Higher elevations typically experience colder temperatures, resulting in higher snow ratios. Mountains may receive significantly more snow from the same rainfall amount compared to lower elevations due to temperature differences of 10-20°F or more.
Snow Water Equivalent (SWE)
Snow Water Equivalent represents the amount of liquid water contained in snowpack. This measurement is critical for water resource management, flood forecasting, and agricultural planning.
What is SWE?
SWE measures how much water would result if snow melted completely. A snowpack with 10 inches depth and 10% water content has a SWE of 1 inch. This metric helps hydrologists predict springtime water availability and potential flooding.
Calculating SWE
Snow density varies from 0.03 (3%) for very light powder to 0.50 (50%) for wet, compacted snow. Average mid-winter snow has approximately 10% density, making the 1:10 ratio a practical estimate.
SWE Calculation Example
Given: 20 inches of snow with 8% density
Calculation: 20 inches × 0.08 = 1.6 inches SWE
Result: This snowpack contains 1.6 inches of water
Why SWE Matters
- Water supply forecasting for reservoirs and agriculture
- Flood risk assessment during spring snowmelt
- Avalanche hazard evaluation in mountainous regions
- Climate monitoring and historical precipitation records
- Ski resort snow quality reporting
Related Precipitation Conversions
Rain and snow measurements connect to various other precipitation and water depth calculations.
Rain to Sleet
Sleet forms when rain freezes before reaching the ground. The ratio is typically 1:2 to 1:3 (rain to sleet) due to its ice pellet composition.
Rain to Hail
Hail accumulation varies widely based on hail size. Large hail events can create depths similar to heavy rain, but measurement is complex due to irregular shapes.
Snow to Ice
Compressed snow eventually forms ice. Fresh snow compressed to ice reduces depth by approximately 80-90%, depending on initial snow density.
Rainfall to Runoff
Not all rain becomes runoff. Infiltration, evaporation, and absorption reduce runoff to 10-50% of rainfall depending on soil type and saturation.
Precipitation Depth Measurements
All precipitation types are ultimately measured by their water equivalent. Rain gauges collect liquid precipitation directly, while snow measurements require melting or density calculations to determine water content. Standard weather stations report both snowfall depth and liquid equivalent to provide complete precipitation records.
Frequently Asked Questions
How much snow does 1 inch of rain make?
On average, 1 inch of rain produces approximately 10 inches of snow. However, this ratio varies significantly with temperature. At 30°F, you get about 10 inches of snow, while at 15°F, the same rainfall creates 20 inches of snow. In extremely cold conditions below 0°F, 1 inch of rain can produce 40-50 inches of light, powdery snow.
At what temperature does rain become snow?
Rain typically transitions to snow when surface temperature drops to 32°F (0°C) or below. However, snow can fall at temperatures up to 36-39°F if humidity is low and the air aloft is sufficiently cold. The most reliable snowfall occurs when temperatures are consistently at or below 28°F.
Why do snow ratios vary so much?
Snow ratios vary because temperature affects snow crystal formation. Warmer temperatures near freezing create large, wet snowflakes with more water content, resulting in lower ratios (1:10 or less). Colder temperatures produce smaller, intricate ice crystals with more air space between them, creating fluffy snow with higher ratios (1:20 to 1:50). Humidity, wind, and atmospheric conditions also play significant roles.
How do you measure snow water equivalent?
Snow water equivalent is measured by either melting a snow sample and measuring the liquid water, or by using specialized instruments like snow pillows and acoustic sensors. Meteorologists collect snow cores using tubes, melt the snow, and measure the resulting water depth. This measurement tells hydrologists how much water is stored in the snowpack.
Can you get snow at 40°F?
Snow rarely reaches the ground at 40°F because snowflakes melt during their descent through warm air. However, if the air aloft is very cold and humidity is low, snow can briefly fall at temperatures slightly above freezing before melting. Any accumulation at these temperatures is unlikely and would be minimal.
What is considered heavy snowfall?
The National Weather Service defines heavy snow as snowfall rates exceeding 1 inch per hour or accumulations of 6+ inches in 12 hours. Heavy snow warnings are issued when 6 or more inches are expected in 12 hours, or 8+ inches in 24 hours. This typically requires at least 0.6 inches of rain equivalent at normal snow ratios.
How accurate are rain to snow calculators?
Rain to snow calculators provide estimates based on temperature and standard ratios. Actual snowfall can vary by 20-30% from predictions due to localized weather conditions, humidity variations, wind patterns, and elevation changes. These calculators work best for general planning and are most accurate when temperatures are stable throughout the precipitation event.
What is the coldest temperature for snow?
Snow can occur at any temperature below freezing. However, extremely cold air (below -40°F) holds very little moisture, making heavy snowfall unlikely. The coldest recorded temperatures with significant snowfall are around -50°F to -60°F in polar regions, though accumulation rates are very slow due to minimal atmospheric moisture.
How much water is in 12 inches of snow?
Twelve inches of average snow (1:10 ratio) contains approximately 1.2 inches of water. However, this varies with snow density. Wet, heavy snow might yield 1.5-2 inches of water from 12 inches of snow, while light, fluffy powder might only produce 0.5-0.6 inches of water from the same depth.
Why is mountain snow different from valley snow?
Mountain snow is typically lighter and drier than valley snow because mountains experience colder temperatures at higher elevations. The temperature difference creates higher snow ratios, producing the powder snow prized by skiers. Valley snow often falls at warmer temperatures near freezing, creating wetter, denser snow with lower ratios.
References
National Severe Storms Laboratory (NSSL), National Oceanic and Atmospheric Administration. Winter Weather Frequently Asked Questions. Retrieved from www.nssl.noaa.gov
National Weather Service, National Oceanic and Atmospheric Administration. Snow Ratio Calculations and Liquid Equivalent Precipitation. Retrieved from www.weather.gov
American Meteorological Society. Glossary of Meteorology: Snow-to-Liquid Ratio. Retrieved from glossary.ametsoc.org