Measuring rainfall. That sounds simple enough. Go to store, buy a rain gauge, place it on your deck and wait for it to rain. That’s the procedure if you’re not necessarily going for accuracy.

To gather accurate rainfall amounts, the NWS(National Weather Service) and COCORAHS(Community Collaborative Rain, Hail, and Snow Network) are good places to start for guidelines to site your rain gauge. Regardless of the type of rain gauge you have. We’ll get in to types of gauges in a moment. Whatever type you have, siting and maintenence are the 2 most critical aspects to getting accurate amounts.

From the NWS:

COCORAHS:

One of the biggest obstacles you may face is finding the best location. Things to keep in mind

• Splash from a higher object than the gauge can cause exaggerated precipitation amounts simply by adding additional water in the gauge from the splash.
• A gauge placed under a tree or has obstruction over the opening can lead to lower readings than what actually fell, simply due for the obvious of the rain being redirected away from the gauge.
• A high elevated gauge. Many folks mount weather stations on buildings, roofs, towers etc. These rain gauges will be notorious for reading low. Even with no obstructions causing splash or redirecting of precip. Simply as wind current will force some of the rainfall around the gauge, vs falling in the gauge. The smaller the rain gauge, the worst this aspect will be.

Let’s take a look at what you do NOT want to do:

What’s wrong with that? That’s 1.5″ board will provide plenty of splash. Adding additional water. You would want to mount the gauge so the top is well above the board it’s attached to. Let’s look at some more poor locations

Why Lacross would even make a gauge like this is beyond me. That’s designed not for accuracy. To sell a gauge for simple install. Again, same as above. Splash will cause major inaccuracies.

This one above is even worse. There you are 5″ below the deck rail. The rail is likely at least a 2×4 if not a 2×6, so you’re getting that splash and also a sideways driving rain splashing off the vertical piece. You will consistently be inaccurate with this setup.

This one(above) isn’t terrible, as long as it’s far enough away from any splash from a rooftop, or railing. Refer to guideline for that distance. Those guidelines are there for reasons.

Then you have the 5 in 1 or All in 1 stations that have a anemometer attached to the station. Folks who want good wind readings will often place these up on the rooftop. Keep in mind, roof slope can also enhance actual windspeed. That windspeed will also do what. It will cause the gauge to under report. Why? Turbulence around the gauge will cause falling rain to be forced around the object vs falling in. High mounted gauges are not the route you want for accurate data.

The type of siting above will lead to multiple faulty data sets. 1- Your temperature will read high during light winds, and high solar radiation. It will also read higher at night vs the standard 2m sensor height in which what most temperature data comparison is based on. 2- Strong winds being forced up the roof will cause exaggerated gust readings. 3- As mentioned above. That smaller gauge will have precip forced around it by wind. Let’s look at more examples:

That setup will under report rain for the same reasons. It won’t be comparable for night min temps when conditions are calm. It’s possible to also gather a little splash at times. The overall uncertainty, if you’re going for accuracy make this to be avoided. It is a downfall to the all in one stations, attempting to place the anemometer how you want it, when the temperature sensor and rain gauge are all together. It’s a challenge.

Another brand of all in one, that can suffer from similar issue below

Not only does that type of site have issues when the station is working well, it’s also a much more difficult location to maintain. To clean. To make sure the station is functioning well.

Those type of 5 in 1 use the tipping style mechanism gauge to record rainfall. A look at a bigger tipping bucket and the inside.

Rain enters in a funnel up top, goes to the tipper and is measured electronically for every tip. Some issues that tipping buckets face. 1- The funnel can become plugged with debri. 2- Spiders etc can build inside and impact the sensitive tipping aspect of the instrument. 3- unless heated(most arent) you will not be able to gather accurate winter time precip. You won’t do that with the smaller deck household rain gauges either. Some folks think they can allow winter precip to fall in their rain gauge and wheh it warms and melts, that’s how much liquid was in the snow. Due to wind, sublimination, often the gauge size will not even hold most of it, will lead to great errors vs actual precip. That said, properly sited, maintained tipping buckets are a super route to go for accurate measurements.

Another new and in my opinion poor route if you’re going for accuracy. A haptic rain sensor. Tempest is a brand that uses these. They measure vibration as the drops hit the surface of the gauge

While the popularity of all in one stations grow, there is so many things here that can go wrong. At times this may work fine. You also can get other things(birds,leaves, strong winds shaking the station) that lead to inaccurate readings and if you go online, you’ll find an array of issues.

The most tried and true method is the standard 8″ gauge(below) used by the nation’s coop observers. Observers following siting guidelines provide valuable data and long running data. For winter, the funnel is removed to collect winter precip to melt or weigh for liquid equivalent.

The cocorahs program which is a growing network uses a 4″ plastic gauge (below)that also has a tube and funnel.

As the gauge grows smaller in circumference, strong winds can impact the gauge at times. Notice here the post cut at a slope away to prevent splash. Here again, the funnel and tube removed to collect winter precip. With winter precip, there is a degree of error depending on snow type, if it builds on the rim etc than can alter how much snow enters and impact actual numbers. As you go from a 8″ opening to a 4″ opening, especially if there is wind, your catch will be less. This can often lead to some inflated ratio reports.

Another high end setup is the weighing gauges. This from Apogee who makes this particular one:

Weighing Precipitation Gauges

The principle of weighing precipitation gauges is the measurement of weight of accumulated water via a sensitive weighing platform. A major advantage of weighing precipitation gauges is the ability to measure total precipitation–liquid or frozen–without the large power requirement of a heated inlet. However, weighing precipitation gauges can be fitted with a heated inlet to prevent snow from bridging/capping over the inlet.

Not a cheap addition to gather precip amounts. Maintenence is important with these. Added antifreeze, mineral oil. The main attraction to these is the recording of frozen precip. That particular style in my opinion, may inhibit in windy setups precip either snow or rain from entering as it should. The size though of 8″ openings does help

This also from Apogee:

Weighing vs Tipping Gauges

Tipping bucket gauges can be used to measure frozen precipitation, but they require a heated funnel to melt the snow, and supplying power for the heater is often difficult or impossible at many field sites. Weighing gauges can measure solid precipitation without the need for heating, although we offer heated inlet options to prevent snow capping. In addition to being preferred for hail and snowfall, weighing gauges are more accurate for measuring all forms of precipitation, particularly at high rates. Weighing gauges can also measure smaller amounts of precipitation. Weighing gauges are more sensitive than tipping gauges, and events as low as 0.025 to 0.05 mm can be detected. Weighing gauges are becoming more widely used because of their advantages over tipping bucket gauges, particularly in regions with mixed or solid precipitation.

There are many companies that make these, some lower in cost, some much higher in cost.

Back in 2002 the USCRN (Climate Reference Network) program began. They go to great lengths to accurately measure precipitation

one very similar to the one above exists at Canaan Valley State Park. Listed as WV Elkins 21 ENE . They build what looks almost like a snowfence around to inhibit wind around the gauge to limit the impacts as earlier mentioned.

The wind breaks are mimicked by other companies to limit the same impacts. This station by Campbell Scientific installed by PSU at Mt.Davis is designed to work in the same manner, albeit much less elaborate

So in summary, while there are many types of rain gauges, it’s important to keep in mind of the location site. You can get high quality and nearly just as good data with a simple $5 rain gauge vs a $500, or $5000 gauge if it’s sited correctly. If it’s not, it doesn’t matter what you spend, your data will suffer. Splash, wind, defection can impact what enters the gauge regardless of gauge type used. Be aware. Mechanical functioning gauges require maintenence. Manual gauges require you to be present and aware of each event.

Regardless of the type of gauge, your options of site location. Give it your best effort. Record it daily. Write it down. Find or create a chart to monitor your amounts. Try to keep your recording interval consistent. Most NWS coops and Cocorahs observers are 7am reports. Whatever falls from the previous morning at 7, through 7 of the morning of observation will go in at that day. Automated tipping gauges can use midnight to midnight. That’s much easier when automated. As long as you detail obs time, keep that time consistent you can create some good running data.