How to Use a Rain Gauge to Measure Rainfall

Last Updated on October 31, 2021 by Phil

Outdoor plants rely heavily on rain for water. Thus, knowing how to use a rain gauge to measure rainfall goes a long way in helping you achieve proper moisture for your plants.

Rain gauges not only let you save money on your water bill, but they also prevent you from accidentally overwatering your plants because it happened to rain a lot the past 2 weeks.

The best thing about the rain gauge is that it is easy to use and inexpensive.

Table of Contents

What Is a Rain Gauge?

A rain gauge is a tool that’s used to measure precipitation. Often, it is used to determine how much rainfall there is in a certain area. Although some people also use it to measure the amount of snow, hale and sleet as well.

Rain gauges can vary from the simple all he way to the very complex. However, for gardening and landscaping purposes, you only need the basic or standard rain gauge.

This makes it an inexpensive, yet invaluable tool that will help you figure out how much water your plants are actually getting. In doing so, you can determine if your yard or garden requires supplemental water or not.

If also prevents overwatering which is one of the leading causes of plant death.

Basic rain gauges are often composed of a simple glass or plastic cylinder. On the sides, they container markings often in inches to help you easily measure how much total moisture there it.

How Does a Rain Gauge Work?

As mentioned, most garden rain gauges are simply a cylinder that collects rainfall. The cylinder can be made from glass or plastic so you can easily see how much water has been collected. And, you match the level of the water in the tube to the unit of measurement (usually in inches) on the side of the cylinder.

More importantly, rain gauges are calibrated so that the 1/10 of an inch or rain will show up as an inch in the rain gauge measurement units. The funnel is likewise designed to be 10 times to cross section of the entire tube.

This scales down the measurement so that that the rain gauge can measure a little as 0.1 inches or at times even 0.01 inches of rain.

Rain gauges are best used to measure the specific amount of rainfall:

In a particular area
At a given time period

Because the coverage of the rain gauge is limited (each rain gauge can only measure precipitation around that section of a large plot of land), you may need to use several sample points to get a better gauge of how much rain actually falls in different areas of your yard. This is especially true if you own acres of land.

Similarly, the limited size of the cylinder makes it most effective to check rainfall for specific time intervals.

This way you can tell the difference between the amount of rainfall in the beginning of spring and the end of spring or any other time of the year.

Can a Rain Gauge Measure Snow?

Well, yes and no.

That’s because a rain gauge technically does not measure snow. So, it won’t be able to tell you how much snowfall there actually was for a given time period.

However, you can estimate that using a rain gauge.

The reason is that rain gauge measure precipitation. That means moisture. So, when snow falls, the instrument does not measure snow. Instead, you’ll need to wait for the snow in the cylinder to melt, then measure the amount of water the snow amounts to.

The problem is that sometimes half a foot of snow will come out to about a quarter inch of water. But, other times, it can equal more than an inch of water when melted.

On average 5 inches of snow comes out to about half an inch of water. But again, it can vary so you can’t be precise with it.

As such, with experience, you can get a good feel of how much snow in your area comes out to using a rain gauge. But, you can’t rely on those same estimates for another part of the city, state or country.

Types of Rain Gauges

There are many types of rain gauges. They range from the very simple which your can DIY at home to the very big, complex and expensive.

However, for gardening purposes, all you really need is the basic rain gauge. This is simple, easy to use and inexpensive.

Just to be through, I’ll go briefly into the other kinds of rain gauges so you know what they are when you see them. And, in case you feel that you may need to upgrade in the future.

Basic/Standard Rain Gauge

The standard rain gauge goes by many names. This can include:

Basic rain gauge
Manual rain gauge
Non-recording rain gauge

I’ve described this above. It is basically a plastic cylinder with units of measurements on it.

The measurement units are calibrated so that you can easily read the amount of rain in inches. In some cases it will be in millimeters, which take a little bit of converting.

The calibration is done by a factor of 10 in order to allow the rain gauge to measure small amounts of precipitation and give you a relatively accurate estimate of how much rainfall has occurred without having to measure your entire yard.

In general, basic rain gauges will go down to a 10^th of an inch. This way you can measure something like 1.6 inches of rain or 1 and 3/10 inches of rain.

Automatic Rain Gauges

Automatic rain gauges are also sometimes called recording rain gauges.

As you can guess, these are more complicated and costly. They are also electrical as opposed to manual. That’s because they have the ability to record the levels of rain

For home gardeners, using automatic rain gauges are a bit over the top unless you really have a large gardening operation or are doing it commercially.

In most cases automatic rain gauges are used for monitoring weather as opposed to gardening.

Tipping Bucket Rain Gauge

The tipping bucket rain gauge uses a very different method compared to the basic rain gauge. It is composed on two buckets that tip to one side or another depending on how much water there it.

Rainfall is collected by a receiver that sends the moisture down a funnel. Under the funnel, there are two buckets that pivot much like a seesaw so that only one will get filled at time.

Once that bucket gets enough water, its weight will cause the bucket to tip so its contents goes into a container. This tipping process also brings up the other bucket which will then collect the rainfall from the funnel.

This process keeps repeating and the amount collected in the container is recorded to a sheet.

Tipping buck rain gauges are used by some weather stations to record precipitation.

Weighing Rain Gauge

The weighing rain gauge works very differently from the tipping bucket rain gauge.

This device only uses one (but bigger) bucket that’s place on top of a weighting mechanism. The bucket’s job is to collect moisture from rainfall.

As it collects more rain the bucket gets heavier. And, the weighing mechanism underneath it will make specific recordings to keep track of the amount of precipitation.

The plotted values will give you a chart-like sheet that shows a curve depicting how much rain occurred within a specific time period.

Floating or Natural Syphon Type Rain Gauge

The floating rain gauge works very much like the weighing bucket rain gauge.

It uses a funnel that collect rainfall then pours int into a rectangular container. At the bottom of the container, there’s a float that will rise with the water as the level rises.

The movements are likewise recorded by the device.

How to Read a Rain Gauge

One of the best things about rain gauges is they are very simple to use and read.

All you need to once the rain is collected in the cylinder is to read the units of measurements to the side of the cylinder.

Often, these units are listed in inches. And, the increments are at a tenth of in inch.

So, if you get 1 inch and 7 tenths, it means that the amount of rain was 1.7 inches for that given period.

Here’s a video showing you how to read a rain gauge with some text practice questions.

Where Do You Place a Rain Gauge?

I’m an analytical person by nature. As you can guess, I do a lot of experiments in my garden.

Among those I’ve done is with the rain gauge.

Most people will just stick the rain gauge in one or two areas and be done with it. I, on the other hand , place it in different sections of the garden to get a better idea of what kind of precipitation each area receives.

I also do it during different times of the year to help me adjust based on the reasons. Although, the differences are not a significant because I live in Southern California. Also, we tend to be on the dry (or drought) side of things.

However, in many parts of the country, the difference in amount of rainfall will vary quite a bit based on the time of year.

From all the trial and error I’ve done, I’ve found that

Garden beds, slopes and areas with many taller plants tend to affect how much water those areas get.
You want to avoid any structure be it natural or man-made. This includes trees and shrubs as well as buildings and other tall objects that can block the rainfall.
Windy areas also affect how rain falls. If there are objects in the way, wind can push the rain towards those objects which affects how much or little rain falls in that space.
It is very important to keep your rain gauge on level ground.

How to Use a Rain Gauge

Most plants need about an inch of rain a week. Thus, using a rain gauge, you can tell whether or not your plants need more or less water.

That said, the actual amount of water a plant needs will depend on the plant. Some plants like more water while others prefer drier conditions.

Just as importantly, rainfall varies throughout the year. It is drier during the summer and wetter in the fall (in most regions). As such, you can use a rain gauge to fully understand the your climate and level of precipitation all year round.

Finally, there’s landscaping. Some areas will receive more rain while other areas. For example, soil that’s beside your house or a structure may not receive as much rainfall because some of it is blocked when it rains from a certain direction.

Similarly, areas near or under trees and other natural landscapes will also likely receive less water.

In the same way, uneven areas of your garden may experience different amounts of rainfall.

As such, you’ll want to use a variety of different positions, times of the year and other parameters when using your rain gauge.

Here’s a video that explains how to use a rain gauge.

Using a Rain Gauge to Measure Sprinkler Output

In addition to measuring rainfall, another useful way to use your rain gauge is to measure sprinkler output.

You probably already know that sprinklers spray water around your lawn and garden in an uneven manner. Some areas get more moisture while other areas get less. Plus, the slope of your landscape also affects where the water eventually ends up in.

Split Your Garden into Sections

Measuring the amount of water your sprinkler produces is a bit tricky for gardens. It is easier for lawns since the surface is usually even and there are no trees, shrubs and plants that block any of the water.

As such, when measuring sprinkler output, it is easier to split your garden up into sections.

You specifically want to know how much water the plants are getting, not necessarily the open spaces.

You’ll also need to label each section of your garden so you can measure the amount of water they receive individually.

That way, you can customize your watering schedule for each section of your garden based on the plants that are there and how much water they receive from the sprinkler.

Measure by How Much Water Your Sprinkler Can Deliver

Another option is to go by time.

Since most plants need around 1 to 2 inches of water a week, you can measure how long it takes for the sprinkler to deliver that amount of water.

You can do so by running the sprinkler for about 30 minutes. Then, check the rain gauge to see how much water has collected. You can then adjust the time period or the flow rate of your sprinkler so it will deliver the proper amount of water on a weekly basis.

How to Know How Much You Need to Water Different Plants

Rain gauges are a great help especially if you have different kinds of plants and different types of garden soil in your garden.

Because there are so many factors affecting how much water your plants receive, I always like to check by hand.

If you stick your finger into the top soil down 2 inches and it feels dry, it is time to water. When that happens, I like to place the rain gauge in there and start experimenting on that area. This will tell my why it is short on water.

Doing that, you can figure out what’s causing one area to have more water than others. There could be runoff, it may be the wind or something might be blocking the rain or sprinkler from reaching that section of your garden.

Additionally, keep in mind that raised beds, like potted plants, will need more watering since the soil dried out faster. As such, they will need supplemental watering (by hand) compared to the rest of your garden.

Finally, the type of soil you have will affect how deep one inch of rain will reach. Clay soils or compacted soils are harder to penetrate compared to loamy or sandy soil.