Introducing the new
Premium CoCoRaHS Gauge

A rain gauge that is easy to use and incredibly accurate.
Order Your TROPO Gauge

Approved By


Five stars
Tyler Johnson

I’ve recently purchased the Tropo rain gauge, and it has been excellent. It is very accurate and best of all easy to use. I really enjoy the forethought that they had designing this gauge all the way down to the accessories that it came with. The brush I didn’t think I’d really need, but it really comes in handy more than I would have thought. If you’re having reservations buying this product… don’t. I highly recommend it!

Five stars
Mike Jewell

Loving this rain gauge. It is so very well designed, manufactured and packaged. I drove a metal fence post in the ground and had it mounted and ready for rain in about 30 minutes. I have a Davis electronic, automated rain gauge that is super convenient to use/read but it's nowhere near as fun as actually seeing the water collect and getting a much better "feel" for just how much rain is 0.02 inches. Or 1.67 inches! Well done Climalytic!

Five stars
Brian Hamilton

This Rain Gauge is without a doubt the most well thought out and quality made gauge out there in the 4 inch category. Tye the inventor of the rain gauge put a 110% effort into its creation, and thought of everything.It is a well built QUALITY product ,and tested for complete accuracy. All of the extras you need to install and maintain the gauge are included! If you are SERIOUS about measuring Precipitation…. Look no further, just order this gauge! YOU WILL NOT BE DISAPPOINTED! It’s a Top Shelf product…..from a Top Shelf Family Company. Finally their Customer Service is Amazing. As they say……JUST DO IT!

Five stars
Carl Compton

I got my new TROPO gauge installed today, very easy to work with. I was very impressed with the packaging and excellent quality of the gauge!!! A very SATISFIED CoCoRaHS observer!!! I would recommend this gauge to anyone!!

Five stars
Michael Sandler

The Tropo rain Gauge solved a number of problems I had with the Stratus Gauge I've been using for 30+ years. I need to mount the gauge on a pole to get it high enough to avoid the community sprinklers. I had the Stratus mounted to the pole using Bungee cords, not exactly ideal. The tropo with the included ties mounts securely to the pole. I also had problems with bird poop which the included bird spikes should take care of. It is also, much easier to put the tube back in, it balances nicely compared to the Stratus. It is also easier to read the rain accumulation and the spout & handle makes it easier to pour amounts over 1 inch. Great Job, highly recommended!

Five stars
Kevin S.

The Tropo rain gauge is great. It is made with high quality materials that give it a great fit and finish. It is also extremely clear, which makes taking readings even easier. I also love that the top snaps on keeping it in place, and that the inner tube has the funnel built into it making the whole thing easier. I highly recommend to anyone looking for a high quality gauge.

Five stars
Ric W.
New Hampshire CoCoRaHS Observer

From careful measurements by weight it is clear that TROPO is more accurate than similar 4" rain gauges on the market. The longer inner tube is easy to read. I expect TROPO will be the premier manual rain gauge for years to come.

Five stars
Cheryl J.
Southwestern Oregon NWS & CoCoRaHS Spotter

Sleek design, highly accurate, easy to mount, and simple to use. Some highlights that will not disappoint: Easy slide on/slide off secure/sturdy mounting bracket, convenient pour spout on the large tube and a brilliantly designed handle that slides onto the outer tube's mounting bracket to pour off your precipitation in excess of 1" into the inner tube. An excellently designed rain gauge.

Five stars
Michael D.
CoCoRaHS County Coordinator, Putnam County, Tennessee

Team, I wanted to encourage you in the development of this great, new product. You all have certainly made great strides in bringing us the next generation for CoCoRaHS observing. You've also thought of much more during development than I could have ever conceived.

CoCoRaHS Statement

"CoCoRaHS Headquarters is pleased to designate the TROPO rain gauge, manufactured by Climalytic Instruments, LLC, as another approved manual 4-inch rain gauge for CoCoRaHS. Field testing has demonstrated the TROPO rain gauge is accurate, and it incorporates observer-friendly features such as greater capacity, improved mounting bracket, and multiple mounting options."

The next gen precision precipitation gauge

The TROPO Precipitation Gauge is the next generation 4-inch all-weather professional precipitation gauge that meets the accuracy and specification requirements of CoCoRaHS. It’s the first comprehensive refresh of the Stratus Precision Rain Gauge, which was first introduced way back in 1973 – almost 50 years ago! Based on the design of NOAA’s National Weather Service official standard 8” rain gauge, the TROPO Precipitation Gauge uses the same dual cylinder design to measure precipitation with a resolution of 0.01” (.25 mm). The inner cylinder holds 1 inch (25 mm) of precipitation, while the extra-large outer cylinder holds another 12.5 inches (317.5 mm) of precipitation when the inner tube is full. The inner cylinder and funnel top cap are removable to allow catchment of snowfall or other frozen precipitation, which can then be melted down or weighed to determine a liquid equivalent. This new gauge offers over 12 new distinguishing features that makes it the most advanced, accurate and easy-to-use manual precipitation gauge on the market.

The Climalytic Precipitation Gauge separated in to pieces.The inner tube for the TROPO precipitation gauge.The outer tube for the TROPO precipitation gauge.The cap for the TROPO precipitation gauge.
Larger Capacity

Approximately 2.3 inches (58.4 mm) of greater capacity than the Stratus gauge, allowing for fewer overflows and longer multi-day accumulations.

Easy To Use

Makes handling and operating the gauge much easier.

High Accuracy

Promotes higher accuracy measurements given longer inner cylinder.

Citizen Involvement

Encourages more involvement in citizen science given the thoughtful, easy-to-use design.

Simple Installation

Simplifies installation.

Longer Outer Cylinder

Offers a longer outer cylinder for making snow core samples of deeper snowpacks.

Strong Materials

Is made of state-of-the-science, UV and weather resistant Polycarbonate materials.

Pour Spout

The spout on the outer cylinder makes it easy to pour out water.

Product Specifications

Size, without bird deterrent rods (L x W x H):
4 in x 4 in x 18.19 in (102 mm x 102 mm x 462 mm)
1.68 lbs, (762 g)
Maximum Capacity:
approximately 13.5” (342.9 mm)
+/- .01” (.25mm)
  1. Bracket & handle: UV stabilized Polycarbonate/acrylonitrile butadiene styrene (PC/ABS)
  2. Cap funnel & cylinders: UV stabilized Polycarbonate
  3. Bird deterrent rods: Stainless steel
  4. Zip ties: UV resistant nylon
  5. Wood screws: Zinc-plated steel

What's Included

• Handle
• Universal Mounting Bracket
• Bird Deterrent Rods (x8)
• Cap/Funnel
• Inner Tube (with dual unit increments)
• Outer Tube (with dual unit increments)
• Cable Ties (x2)
• Wood Screws (x2)
• Adhesive Strip
• Extra Long Cleaning Brush
• Bubble Level
• Installation Guide

All of the main pieces of the TROPO precipitation gauge: the outer tube, inner tube, cap, bracket, handle and anti-bird rods.

Stratus vs. TROPO

Resolution to the nearest .01” (.25 mm)
Removable cap for capturing & measuring water equivalent of snow, hail, sleet or ice
4 inch diameter opening
CoCoRaHS approved
Cross Mark
Lasting clarity
Cross Mark
Units in both metric & imperial
Cross Mark
13.5” (342.9 mm) maximum capacity
Cross Mark
Textured grips on outer cylinder for secure handling of the gauge
Cross Mark
Removable bird deterrent rods
Cross Mark
Funnel opening atop inner cylinder
Cross Mark
Outer cylinder graduations for quick, estimated readings
Cross Mark
Removable handle for easy handling of the unmounted gauge
Cross Mark
Flexible mounting bracket for pole or post installation
Cross Mark
Weather-protected bracket design for easy mounting & unmounting
Cross Mark
Inner cylinder equipped with stabilizing base for easy filling
Cross Mark
Locking funnel cap to avoid blow-offs
Cross Mark
Easy, no-tool installation to pole
Cross Mark
Tall cap for more accurate catchment of precipitation
Cross Mark
Beveled guide ensures easy placement of inner cylinder
Cross Mark
Pour spout on outer cylinder
Cross Mark
Includes bubble level and cleaning brush
Cross Mark


Is the TROPO precipitation gauge an approved device for CoCoRaHS observers?

Yes! It is the “premium CoCoRaHS gauge” and is an approved gauge for measuring precipitation for the CoCoRaHS network.

Was the TROPO gauge tested and evaluated by qualified weather observers?

Yes! Ten carefully-selected field testers across the United States critically evaluated the features, measurements, and accuracy of the TROPO gauge. The 2-month long field testing and evaluation campaign addressed (1) installation, (2) handling & features, (3) measurement and accuracy, and (4) the user guide. The field testing campaign helped inform final design tweaks to the TROPO, edits to the user guide and solidified endorsement by CoCoRaHS. For a very comprehensive and independent scientific evaluation of the TROPO, visit

CoCoRaHS training videos and other documentation indicate the weight of 1.00 inch of water is 201 grams, but the TROPO users guide and FAQ say 1.00 inch of water weighs 206 grams. Why the difference and which should I use?

The true weight of an inch of water in a four-inch diameter cylindrical vessel is 206 grams, but when filled to the 1.00 inch mark on the Stratus gauge, it only weighs 201 grams. The Stratus gauge has a known and documented error, but in order to keep your measurements consistent with the gauge you're using, CoCoRaHS recommends that if you own a Stratus gauge, divide the weight of precipitation by 201. If you own and use the accurate TROPO gauge, divide by 206.

I fear the condensed water vapor and rain droplets clinging to the sides of the inner and outer tubes is not contributing to the measurable amount of rain in the gauge and sometimes makes it hard to read the guage. What can I do about this?

The TROPO is designed to minimize evaporation loss from the gauge, but sometimes condensed water from evaporation is trapped within the gauge and rain droplets themselves cling to the sides of the tubes from surface tension. This amount of water is negligible and only amounts to about .005”, or less, and does not impact your measurements. However, if there seems to be excess water not in the bottom of the inner tube, you can round up your measurement to the nearest 0.01 inch. To minimize the surface tension of the water, try using Rain-X® Plastic Water Repellent Trigger. This is specifically designed to repel water from polycarbonate plastic and it will not harm the gauge.

How do I know the TROPO is correctly calibrated?

Knowing that one inch of water equals 206 grams within a 4-inch diameter cylinder, we used a CoCoRaHS-approved scale, and tared the scale (to 0) with the gauge on the scale, then poured water into the TROPO until it reached 206 grams and then checked to make sure the meniscus was at the 1.00” marking on the inner cylinder. And sure enough, it was perfect.

Why do I get different precipitation measurements from my TROPO vs. other popular 4” precipitation gauges?

This could be due to numerous reasons, but assuming all things equal, the primary reason is because the TROPO gauge is perfectly calibrated whereas other popular 4” rain gauges are not. During our calibration, testing and comparison evaluations, we found that the “Stratus” All-Weather precipitation gauge and the “Outback Blue” precipitation gauge were off by about 4%. In other words, when the Stratus inner tube was filled with 206 g of water, which is mathematically equivalent to 1.00” of water, .04” of water overflowed past the 1.00” marking.

When taking a snow core sample, won't the pour spout collect excess snow, resulting in an inaccurate snow water equivalent (SWE) measurement?

Technically excess snow may end up in the outer tube, but the spout is very small and its impact on the snow core sample/SWE is negligible. The errors in collecting a representative snow core are much larger than what the small spout would contribute. We discussed this with the CoCoRaHS team and they agree. If you are concerned about this, you can tape off the spout to prevent it from impacting the snow core.

The cap is difficult to remove and re-attach. How can I make it easier to operate?

The extra tall cap on the TROPO is prone to blowing off, so we engineered a way for the cap to snap on without any moving parts. As a result of this tight fit, some may initially find it difficult to remove the cap. For some tips and tricks on how to more easily affix and remove the cap, see the Knowledge Base section below. Alternatively, you can apply a small amount of grease on the 3 dots inside the cap to allow them to snap in/out easier. We also think repeated use of the gauge will eventually make it easier to operate.

How do I use the TROPO in conjunction with a scale to make precipitation measurements?

First, use a scale to determine the weight of the dry, empty outer tube; write the weight down on the bottom of the tube with a Sharpie for future reference. When the outer tube contains precipitation, weigh it and subtract the dry weight of the tube to determine the weight of just the precipitation. Take the weight in grams and divide it by 206 g (or weight in ounces divided by 7.27 oz). For example, if the precipitation weighed 80 g (2.8 oz), the precipitation depth would be 80 g divided by 206 g (or 2.8 oz divided by 7.27 oz), both equate to 0.39 inches (9.9 mm) of precipitation. Easy, fast and accurate!

Why aren’t there lines denoting the different depths on the outer tube so I can make better estimates of precipitation?

This is by design so the outer gradations are not used to provide anything more than an estimate of the accumulated precipitation. For an accurate measurement, you must repeatedly decant the precipitation collected in the outer tube into the inner tube that offers precise measurement gradations.

Where can I buy replacement or extra parts?

To buy replacement/extra parts and other weather instruments, visit our online store at It’s also really handy having at least one extra outer tube so that you can quickly swap out gauges amidst heavy precipitation events at your observation time.

Why would I buy a manual rain gauge when I can get an automatic, self-emptying rain gauge?

View our 2023 Annual American Meteorological Society conference poster (in the Knowledge Base section below) for our top 10 reasons manual precipitation gauges are so important.

Where can I download the installation and user guide?

You can download the user guide and other TROPO resources in the Knowledge Base section below.

How can I share the precipitation data from my TROPO gauge with others to use for drought monitoring, emergency management applications, water supply monitoring and weather forecasting?

There are a number of citizen science organizations and observer networks that value precipitation data. The largest such network is the Community Collaborative Rain, Hail and Snow Network, or CoCoRaHS. CoCoRaHS is a network of volunteer weather observers in the United States, Canada, and the Bahamas.

Do you offer bulk discount pricing?

Yes, please contact us for bulk order discounts and/or reseller opportunities.

How do you know 206 grams of water equates mathematically and factually to 1.00 inch of water in to TROPO, or any other 4” diameter rain gauge?

First compute the volume of 4” diameter (2” radius) cylinder that is 1” long. Using the equation π*r^2*h equals 12.57 cubic inches. Then, we know the density of water, which is not compressible, is 16.387 grams per cubic inch, so if you multiply volume (12.57) by density (16.387) you get 206 grams.

How far up should the top of the TROPO gauge extend above the post, fence or post it’s attached to?

How far up should the top of the TROPO gauge extend above the post, fence or post it’s attached to? There is not an official requirement for this, but to limit splashing from the post or fence into the gauge, or wind under/over-catch impacts, we recommend the top of the TROPO be positioned as far above the post or fence as the bracket will allow. It is strongly recommended that the wooden post be beveled at the top to limit any splashing into the gauge.

What are the dimensions of the TROPO gauge?


Does the TROPO have a warranty?

We offer free replacement of damaged or defective parts upon arrival, but otherwise we don't offer a warranty. The UV-resistant polycarbonate material we're using is slightly flexible and can accommodate some freezing precipitation in the inner tube without damage, but we can not be responsible for misuse of the gauge, including cracked inner tubes as the result of freezing.

What is the life expectancy of the TROPO gauge?

Life expectancy will vary depending on climate and care, but the UV-resistant poly-carbonate plastic is extremely durable and the same material greenhouses are made of. We're confident the plastic will last at least 10 years. The labels were added using a highly durable laser printing technique, which we also expect to last at least 10 years. Assuming a 15 year life span, the cost is only USD $0.018 (1.8 cents) per day!

I want to buy a TROPO precipitation gauge, but the price it too high. How can I buy it for a lower price?

We understand the price might be high for some, but we assure you the TROPO will last longer, preform better and offer a much better user experience than any other 4” gauge on the market. We’ve done our best to keep the price down as much as possible, but if you are looking for a lower price here are some options: (1) Pool together 12 CoCoRaHS observers who want to upgrade and buy a case of 12 of gauges, which drops the individual price down to $74.99 (including shipping!). (2) Wait for another sale that offers a deeper discount. (3) At some point in the future, we hope sponsors will help offset some of the costs for new and existing CoCoRaHS observers.

My TROPO gauge is collecting insects, how can I minimize this?

Looping an elastic insect repellent band or bracelet around the top of the gauge can help. Replace the band frequently for best results. Also, avoid installing the gauge near a light that naturally attracts bugs at night.

It's Time For An Upgrade

Head over to our online store to purchase your TROPO Precipitation Gauge. We offer free shipping to all 50 U.S. States!
Order Your TROPO Gauge