How to Measure Snowfall Accurately

Measuring snowfall with a ruler

You might think measuring snow is as easy as sticking a ruler in the snow. While that’s a great way to get a general idea of how much snow has fallen, if you’re looking for accurate snowfall measurements, there are accepted meteorological standards for measuring snowfall correctly.

We’re about to explain the methods that are especially vital to understand if you’re sharing your measurements with CoCoRaHS or the National Weather Service. Both groups prefer that readings are taken using a standard practice, so they can be compared to other nearby stations accurately.

What do you need to measure snowfall at home? We recommend the following:

  • A ruler (preferably a yardstick)
  • A snowboard (a 16“ x 16” piece of 1/2” or 3/4” thick plywood painted white)
  • A Stratus Precision rain gauge

With these three items, you’ll be able to provide meteorologists with helpful information, including snowfall, snow depth, and the liquid-equivalent of snowfall. Read on to learn how to take accurate snowfall measurements.

Snowfall vs. Snow Depth

The first concept to understand is the difference between snowfall and snow depth. Snowfall is a measurement of snow occurring within a given time frame, typically 24 hours, or measurements taken from “bare ground” during or immediately after a snowstorm.

These readings are helpful to meteorologists as they show how much snow falls from a specific event or time. While many official stations take readings every six hours, cooperative observers and CoCoRaHS participants only need to take a reading every 24 hours.

On the other hand, snow depth measures all the snow currently on the ground, either falling or already present. While these readings are often not helpful in the short term, in the long-term, they can give meteorologists an early warning of possible snowmelt flooding if heavy rain and warm temperatures are in the forecast.

We recommend using a yardstick to measure snowfall and snow depth—this way, you are ready for any size snowstorm. However, if you live in a warmer climate where snowfall is rare, a standard ruler may be sufficient. Just make sure the ruler’s measurement scale starts from the ruler’s edge—some do not.

What Is a Snowboard?

Snowboard being used to measure snow

Image Credit: CoCoRaHS

Official snowfall readings aren’t taken by sticking your ruler into the snow until you reach the ground. Measuring snowfall this way can cause your measurements to be significantly higher than they are. Snow is incredibly light and “floats” on the grass in lighter snows. Your ruler will not only pass through the snow but through this blanket of grass as well—making measurements appear larger.

That’s why official measurements are taken on a snowboard. While it sounds like a more complex weather instrument, it’s just a square piece of white-painted plywood. If you’d like to make one yourself, choose a piece of plywood between 1/2” to 3/4” thick, cut it into a 16” x 16” square, and paint it white.

Can I Measure Snowfall With a Rain Gauge?

Rain gauge measuring snowfall

Image Credit: CoCoRaHS

Yes, you can measure snow with a rain gauge if you have the correct rain gauge. The Stratus Precision rain gauge is the perfect model for measuring snowfall. It’s our top pick in our rain gauge buying guide. With the Stratus, you can remove the inner cylinder and funnel during snowstorms, allowing snowfall to accumulate within the larger tube.

Owning a rain gauge like the Stratus also allows you to take measurements of the “liquid equivalency” of snowfall. As we mentioned previously, this is important for hydrology forecasts, and especially in the spring as snow melts. There are two ways to use your rain gauge to take liquid equivalency measurements, which we’ll explain below. One uses only your rain gauge, and the other uses the snowfall on your snowboard to obtain a “core measurement.”

Where Should Snow Be Measured?

No matter which technique you use below, your measuring location is crucial for overall accuracy. You should take snowfall measurements in an open area away from obstructions like your house or large trees. Your rain gauge or snowboard should be placed at a distance twice as far away as the height of the nearest obstruction.

How to Measure Snowfall Like a Pro

Here are the three different types of measurements you can take to calculate the amount of snowfall in the winter.

Measuring Snowfall with a Snowboard

  1. If possible, place your snowboard outside on a flat level surface at least 6-12 hours before snow begins. This will give the snowboard time to “acclimate” and cool to the ambient temperature, ensuring accurate readings. Place a flag or tall object on the board so you can locate it after it snows.
  2. After a snowfall event, place your ruler on the snowboard area, and measure the snowfall to the nearest tenth of an inch. Take another one or two measurements if the snowfall is uneven across the snowboard and average the measurements together to obtain a more precise reading.
  3. Only clear the snowboard after your regular 24-hour observation. You do not need to clear the snowboard after every measurement.

Snowfall and snow depth are measured to the nearest tenth of an inch on a snowboard. Anything less than .1” is marked as a “trace” of snow. If snowfall melts as it falls, this is also considered a trace.

As most rulers are marked in 1/8” or 1/16” increments, you will need to round your measurement to the nearest tenth of an inch. For example, 6 3/8” = 6.375” = 6.4”.

To obtain accurate and consistent measurements, make sure to measure new snowfall as soon as possible after the storm ends before any melting or settling of the snow can occur.

Measuring Liquid Equivalent of Snowfall With a Rain Gauge

  1. Remove the inner cylinder and funnel from your rain gauge before positioning the gauge outside for winter use.
  2. After a snowfall event, if snow has accumulated on the rim of the gauge, then gently tap on the rim with a fly swatter or spatular and only count what falls into the gauge. Disregard any snow that lands outside the gauge.
  3. Take your gauge inside to melt and measure the snow.
  4. We’ve found the easiest and quickest way is to use hot water to melt the snow. Fill the inner cylinder with hot water and carefully note the amount of water you’re adding.
  5. Pour the hot water from the inner cylinder into the outer cylinder and swish the outer cylinder around in a circular motion to mix the warm water with the snow. The snow should melt.
  6. Once the snow has melted, you’ll want to pour the water from the outer cylinder into the inner cylinder, using the funnel on top to ensure there is no spillage.
  7. The liquid equivalent of your snowfall will be the total measured liquid minus the initial measurement of hot water you added.

The liquid equivalent of snowfall is reported in hundredths of an inch.

Measuring Liquid Equivalent of Snowfall From a “Core Measurement”

  1. If you want to take a core measurement from your snowboard, detach the outer cylinder of your rain gauge from its mount and turn it upside down on top of the snowboard, pressing down until you reach the snowboard’s surface (like a cookie cutter).
  2. Carefully lift the snowboard, turn the snowboard upside down, slide the gauge off to the side, and ensure the core sample of snow stays inside the gauge.
  3. Melt and measure the snow core using the inner cylinder and hot water like the previous method above.

Tips and Final Thoughts

While the process to measure snowfall might seem a little daunting at first, with time, you’ll be able to take these measurements quickly and accurately.

We recommend placing a tray under your workspace to catch meltwater if you’re taking liquid equivalency measurements—this way, if spillage occurs, you might still be able to salvage your measurements.

In very heavy snowstorms (20” or more), and especially those with wind, you should always use a snowboard. You may also need to average several measurements around your yard and estimate snowfall to the nearest inch.

We hope this article helps you measure snowfall on your own at home, and if you have any questions, we’d be happy to help you in the comments.

Published: April 23, 2021

Leave a Reply