What is a Storm Glass

Article Last Updated: November 11, 2020

What is a Storm Glass?  Do Storm Glasses Really Work to Predict the Weather? 

A storm glass is a sealed device made of clear glass that contains chemicals that are said to crystalize to in such a way to predict weather a couple days in advance.  One to three days later, the observed weather should mimic the prediction from a couple days back.  The actual inventor of the storm glass is unknown.  They first starting showing up somewhere towards the mid-1700s, however they became popular after documented use by Admiral Robert Fitzroy. 

Fitzroy was a pioneer in advance weather forecasting.  He was also the captain aboard the HMS Beagle with Charles Darwin during his expeditions researching evolutionary differences in animals.  Fitzroy documented that he used a similar device intended to measure barometric pressure and temperature changes through solubility of the crystals.  For this reason, these instruments are often called a Fitzroy Storm Glass or a storm glass barometer.  This is the same storm glass Fitzroy wrote about in his 1863 book, aptly called, The Weather Book.

How Does a Storm Glass Work?

When something similar was used by Fitzroy back in the 19th century, it was meant to measure barometric pressure, which is actually a good indicator of approaching weather.  However, modern storm glasses have been tested and revealed to actually be more of a measure of temperature than pressure.  Temperature changes don’t tell us much about high or low pressure systems coming into the area or whether it will rain, snow, or be clear outside.  Ultimately, it is this reason that many believe Fitzroy storm glasses do not predict weather well.

The ingredients in storm glasses differ slightly, but most commonly they include ethanol, distilled water, ammonium chloride, potassium nitrate, and camphor.  Some of these chemicals are hard to get your hands on these days, so they are often substituted with something else, including vodka of all things! 

Storm Glass Instructions

Storm glasses typically come with their own set of instructions and how to read them.  Most storm glass instructions are pretty much the same, with little variation.  The premise is that temperatures and pressures affect the solubility of the solution in the storm glass.  This means sometimes the liquid will be clear and other times present a different pattern that might resemble a specific weather pattern.  As mentioned above, temperature certainly affects solubility, but since the storm glass is a sealed glass container, pressures don’t really have much affect on them. 

The most important part of storm globe instructions are the charts and/or pictures that are associated with how they are read.  Both the chart version and the picture version can be seen below as an example of what might come with a purchased storm glass and how to use one.

How to Read a Storm Glass

Storm Glass Observation Weather Prediction
Cloudy liquid with small spots Storms
Clear liquid Bright & sunny
Small spots in winter months Sunny, but snow coming
Large flakes Overcast sky, snow in winter months
Flakes toward top of glass Winds in atmosphere, weather change coming
Cloudy liquid Either raining or rain coming soon
Strands at top of glass Windy
Small spots suspended in liquid Foggy
Cyrstals at bottom of glass Frost

How to Read a Storm Glass with Pictures

how to read a storm glass

Where to Place a Storm Glass

It is recommended that you place a storm glass indoors, on a level surface.  It’s best for it to be next to a window that gets no direct sunlight.  You should also keep your storm glass out of reach from your children.  If you place it outdoors, it could easily break due to high winds or storms.

How to Make a Storm Glass

If you are interested, there are DIY instructions on how to make a storm glass all over the internet, however some of the ingredients (chemicals) are hard to find.  Here’s a video detailing the process.

How to Make a Storm Glass

Want To Buy One?

Don’t want to learn how to make your own?  You can easily just buy a storm glass from Amazon or any number of other online retailers.  They are actually very reasonably priced, starting around $20 and going up from there, depending on the quality and size of the instrument.  Many of the devices that you can buy today also come with a Fitzroy storm glass chart that provides pictures and descriptions of how to read it.  This will be something similar to what we provided above in the section titled “How To Read A Storm Glass”.


Best Storm Glass 2021

The best storm glass is just the one that you find the most aesthetically pleasing.  Beyond that, it’s best to look at previous customer’s reviews in order to make sure the product is delivered on time, packaged well, and fits the description.  Here are our recommendations for the best storm glass to buy on Amazon:

best storm glass

Teardrop-Shaped Storm Glass

Many other options can be found with a quick search of “storm glass” at Amazon.

Weather Predicting Storm Glass Reviews / Storm Glass Review

It is tough to review this product.  So many of the storm glasses on Amazon are very similar copies of one another.  Our recommendation is not to get a storm glass with the intention of it providing your weather forecast, but rather as a nice conversation starter.  This way you’ll be happy with your purchase.  Your best bet in selecting a storm glass is to find the one with the best customer reviews and one that looks appealing to you.  Storm glass reviews by actual customers who have purchased the item are best.

Cool Time-Lapse Storm Glass Video

Do Storm Glasses Really Work? 

There are some out there that claim Fitzroy storm glasses work.  It is probably true that someone with a trained eye would have better luck predicting the weather with one.  However, I think that’s just what it is, luck.  Through research and testing, it’s been revealed that at least modern storm glass accuracy is not much better than the probability of a coin flip at 50/50.  Buy hey, even the news weather forecaster doesn’t always get it right!

If you’re really looking to forecast the local weather with a device in your home, you’d be better off with a home weather station.  Many of them will take your actual hyper-local weather data and provide you with a 24-hour forecast.

This doesn’t mean you shouldn’t buy a storm glass, however.  They are fun instruments and a great conversational piece now that you know the history behind them.  A storm glass is a great, inexpensive weather-related gift to get for the weather enthusiast in your life.

Storm Glass FAQs

Q:  Who is the storm glass inventor?

A:  No one knows who actually invented the storm glass, although it was first documented Admiral Robert Fitzroy in the 1860s.  Fitzroy was the Admiral of a ship that took Charles Darwin on his excursions.  As mentioned above, this is the reason these instruments are sometimes called a “Fitzroy Storm Glass” or an “Admiral Fitzroy Storm Glass”.

Q:  Is a storm glass accurate?

A:  Some folks swear by them, and more power to those people.  Research and extensive testing has shown that the odds of a storm glass predicting the weather is no better than a coin flip (50/50).  They are not a reliable source of weather prediction.

Q:  My Storm Glass is not working, what can I do?

A:  I don’t think there is anything you can do.  The storm glass not working is because it’s more of a novelty item than a real, functional tool.  Keep it clean and set it out for looks and fun discussions when your friends come over.  Sometimes you get lucky and the charts match the weather outdoors, appearing to give the storm glass meaning.

Q:  Is a storm glass teardrop shape more accurate than other shapes?

A:  No.  In our experience, the shape has little to no effect on storm glass accuracy or functionality.  Teardrops just look really nice, especially when mixed with the crystals inside the device.  We recommend you buy, or make, whatever shape you like the looks of best.

Q:  Does a Fitzroy storm glass work indoors?

A:  It is recommended that you keep a Fitzroy storm glass indoors.  Please see the “Where to place a storm glass” section above.  Keeping it outdoors would put it at risk of breaking if the wind blew it over or it was hit by hail or something else.  It’s also advisable that you keep a storm glass out of direct sunlight so quick temperature changes don’t falsely affect the crystals inside.

Q:  Is a storm glass and a storm globe the same thing?

A:  Basically, yes.  They come in different shapes.  Common shapes are the teardrop you see in the images above, storm “tubes”, and a storm globe.  They all work the same however and are only slightly different from Admiral Fitzroy’s historic storm glass.

Q:  Where’s the best place to buy a storm glass?

A:  Amazon is the best place to find a storm glass.  Amazon has the best selection, the lowest prices, and free 2-day shipping if you have Prime.  

Q:  What are some other names for a storm glass?  

A:  I’ve seen them called an Admiral Fitzroy storm glass (or just Fitzroy storm glass), a storm globe, a storm glass barometer, a weather predicting storm glass, a storm glass weather forecaster, a storm glass predictor, a weather orb, and even a storm glass weather station! 

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