Before the invention of modern forecasting, humans knew how to predict weather by looking at clouds.
So on my quest to learn ancient survival & awareness skills, I decided to investigate what clouds can tell us about the weather.
To predict weather with clouds, you simply have to look at observable patterns like cloud size, cloud shape, altitude, vertical depth, and color shading within the cloud itself.
In general, when you see small, isolated clouds surrounded by a blue sky that lacks significant dark areas or signs of active growth, these are all indicators of fair weather ahead:
Then as clouds begin to expand in size and develop dark spots or occupy multiple layers of the sky, these are indicators of stormy weather developing:
While the basic rules for predicting weather with clouds are fairly simple, many people find this skill confusing because there are so many different types of clouds that all have their own nuances.
In actual practice, weather patterns take many days to evolve so you have to stay alert to what’s happening with the clouds over an ongoing period of time.
There are several different ways the transition from clear weather to storms can occur, so it’s important to know all the stages and how to identify the clouds you encounter as the weather changes.
So let’s go deeper and take some solid steps towards learning how to predict weather with clouds!
How To Read Clouds
The easiest method for learning how to read clouds is to have lots of real-life examples of what clouds look like in different weather patterns.
So for starters, I’ve created this cloud video tutorial to show you some of the most important things you’ll need to observe:
As you can see, reading the clouds is simply a matter of observing basic visual characteristics like the overall size, shape, and relative height of a cloud.
You can practice identifying these patterns in clouds by stepping outside to observe the sky while asking some sorting questions like:
- How big are the clouds?
- Are you seeing low, medium, or high altitude clouds?
- Are there any dark spots or signs of active growth?
- How many clouds are up there?
- How much of the sky is covered?
- How fast are the clouds moving?
As you practice observing the sky with these questions in mind, very quickly you’ll notice there are obvious differences between the size, quantity, color & altitude of clouds.
The next step is using these raw observations to classify and identify different types of clouds that help us predict the weather.
Learning to identify clouds was a huge step on my personal journey to understanding weather patterns, so let’s look at this next.
Eight Different Types of Clouds That Predict Weather
There are eight main types of clouds that everyone should know if you really want to get good at predicting the weather with observation.
Luckily, learning to identify these eight cloud types is surprisingly simple once you know what to look for.
I was able to learn the basics of cloud identification with just a few hours of practice by studying things like altitude, size, and overall appearance, which we’ll cover in this section.
When I first got into weather tracking, I was amazed to discover just how obvious the difference is between low, medium, and high altitude clouds.
In this way, we can further simplify these eight cloud types by lumping them into four categories based on the altitudes where they appear in the sky.
Low Altitude clouds (0-6500 ft)
Medium Altitude Clouds (6500-26,000 ft)
High Altitude Clouds (15,000-60,000 ft)
Storm Clouds (1500-60,000 ft)
Even though I’ve included the numbers in feet, it’s not necessary to know the precise altitude of a cloud because the difference between low, medium & high altitude clouds is so obvious you can see it with the naked eye.
Each cloud type gives us useful information about what’s happening in the atmosphere and helps us predict the upcoming weather.
Some clouds are indicators that predict rain and storms approaching, while others are useful indicators of fair weather ahead.
You’ll also notice that each layer includes a cumulus form and a stratus form.
An important principle here: If you can learn to recognize cumuliform and stratiform clouds at all three layers of the sky, you’ll have everything you need to start predicting weather with clouds.
So let’s take a closer look at how to identify these different clouds:
1. Cumulus Clouds
Cumulus clouds look like little puffballs gently floating through the sky at relatively low altitudes.
In fact, you’re probably already familiar with cumulus clouds whether you realize it or not.
If you’ve ever spent a summer afternoon spotting sheep, elephants & unicorns in the sky, you were probably looking at cumulus clouds.
In layman’s terms, we might call these “clumping clouds” (because they clump together).
The most important thing to observe is how big the cumulus cloud is, and whether there are signs of active growth.
It’s very easy to predict when cumulus clouds are a sign of evolving storms by looking at whether the cloud is expanding or dissipating.
Cumulus clouds are often associated with fair weather, especially when they stay small or wispy throughout the entire day.
When cumulus clouds grow big enough to expand into higher altitudes, they eventually become cumulonimbus clouds, which are storm clouds that we’ll talk about in the section on clouds that produce rain.
For now, just remember to look for signs of active growth or dissipation in cumulus clouds as shown in the image above.
2. Stratus Clouds
Stratus clouds can be difficult to identify because they often appear as a uniform layer of fog that covers the entire skyscape.
These clouds develop at a very low altitude and block out all the sunlight/blue sky, making it very hard to tell what’s happening at higher levels.
The obscured view caused by stratus clouds makes it particularly important to watch the sky over an ongoing period of time and look for general weather trends.
In some cases, Stratus clouds can be associated with storms, but it’s also equally possible to find clear blue skies just above the cloud layer.
This is especially common if you live close to the ocean where stratus clouds are often associated with fair weather as the fog burns off through the day.
For this reason, it’s important to pay careful attention to what other types of cloud activity were happening before the stratus clouds appeared.
If the onset of stratus clouds is preceded by several hours or days of higher altitude clouds gradually moving in and becoming thicker, this is very likely a sign of stormy weather ahead.
In the section on Nimbostratus clouds, we’ll talk about how to predict storms that might be associated with stratus clouds.
But there are still a few other types of clouds we need to know first, so let’s move on to medium altitude clouds!
3. Altocumulus Clouds
Altocumulus clouds are just like cumulus clouds except they happen at a higher altitude of the sky.
This higher altitude makes the clumps appear smaller and farther away giving the sky a mottled blue appearance.
These clouds are often associated with weather systems that grow into cumulonimbus storms (which we’ll talk about in the section on clouds that produce rain).
Essentially this means altocumulus clouds indicate the possibility of stormy weather in the area, but that it’s likely not very close yet.
These clouds can be an early precursor to rain or snow and may occur many hours before any actual storm hits.
In order to determine what altocumulus clouds mean, you need to consider what the weather has been doing over the last week and whether the trend is getting more or less extreme.
If you see altocumulus clouds, keep watching for signs of increasing instability and active growth, especially in other cumulus clouds that could grow to become cumulonimbus.
On the other hand, if you recently had a big storm, then altocumulus clouds could simply be the remnants of what’s already passed by.
The context is important!
4. Altostratus clouds
Altostratus clouds, similar to altocumulus clouds are extremely important for predicting storms.
Notice the layers of cloud streaking out from the horizon. These streaks are caused by wind currents moving in the direction of the spreading pattern.
Altostratus clouds are extremely common to see before the approach of a storm, and they’re responsible for creating beautiful red skies at dawn & dusk.
If you’ve ever heard the saying “red sky at night sailer’s delight, red sky at morn watch out for a storm.” This is a reference to altostratus and altocumulus clouds.
When you see altostratus clouds, watch for a gradual thickening of these cloud layers that slowly gets lower and eventually blocks out all the sun before a storm (more on this when we talk about predicting rain).
5. Cirrostratus Clouds
Cirrus clouds form at very high altitudes, and just like all layers of the sky, they include a cumulus form and a stratus form.
In the photo above we can see examples of both cirrostratus and cirrocumulus, as well as several jet condensation trails.
Cirrostratus clouds have a hazy spread-out look that can appear in patches as shown above or sometimes cover the entire sky.
If you’ve ever noticed a halo around the sun or moon it’s probably because you were looking through the soft haze of a large cirrostratus cloud.
These clouds happen at such a high altitude that condensation occurs in the form of ice crystals, giving these clouds a strange sort of wispy appearance.
6. Cirrocumulus Clouds
Cirrocumulus clouds are high altitude clouds that form in tiny mottled clumps. They look very much like altocumulus clouds, except they’re noticeably higher in the sky.
Cirrus clouds are often the earliest indicator that stormy weather is coming your way.
If you want to know whether cirrus clouds are a sign of storms ahead, look for signs of increasing instability on the middle and lower cloud levels over the next 24-48 hours.
If Cirrus clouds gradually become thicker and more pervasive, followed by gradually increasing altocumulus or altostratus clouds, you’re probably observing the approach of a weather system.
More on this in the next section on how to predict rain.
Clouds That Produce Rain
The two main types of clouds that produce rain are known as Nimbostratus clouds & Cumulonimbus clouds.
It’s important to point out a defining feature of storms is their associated clouds occupy multiple layers of the sky simultaneously, from 1500 ft all the way to 60,000 ft).
For this reason, one of the easiest ways to predict storms is to look for increasing cloud activity that spans to cover low, medium, and high altitude clouds all at the same time.
This is surprisingly simple once you get the hang of it.
6. Nimbostratus Clouds
Nimbostratus clouds are simply stratus clouds that have become so big and dense, they drop rain or snow.
Notice in the above photo, you can’t even tell where the cloud begins and ends. It’s very dark, grey, relatively featureless compared to other types of clouds and covers a large area of the sky.
As a result, nimbostratus clouds can be difficult to identify on their own.
However, by the time a nimbostratus cloud arrives there typically have already been many signs of a storm developing for many hours or even days.
Nimbostratus is commonly associated with altostratus clouds, so that’s often the easiest way to predict the approach of these storms.
Nimbostratus clouds produce large amounts of rain and also snow during cold weather.
In a slow-moving weather system, these clouds can stay overhead and rain in a looming way for days at a time.
This is very different from the other main type of cloud that produces rain.
7. Cumulonimbus Clouds
Cumulonimbus clouds are essentially just very big cumulus clouds that have grown so large that violent rain comes out the bottom.
This type of rain is often produced by warm, humid air rising on thermals in the summertime. This is sometimes called summer rain.
When cumulonimbus storms get big enough, they can produce intense lightning, hail, and even tornadoes.
These clouds drop a large amount of precipitation in a very short period of time, but the overall rain event typically lasts for much less time than nimbostratus rain.
In this case, it’s not uncommon for the morning to start out sunny, followed by pouring rain for an hour in the afternoon, and sunny again at 3PM.
Cumulonimbus clouds also have the greatest vertical depth of any cloud and frequently extend all the way through the lower, middle & even upper levels of the sky in a single cloud.
How To Predict Rain With The Clouds
As stated above, if you want to predict the approach of rain, it’s not enough to simply identify rain clouds in the sky.
We really need to be able to predict the approach of nimbostratus and cumulonimbus clouds BEFORE these clouds arrive.
Depending on the size, type, and intensity of a storm, early signs can be seen anywhere from a few hours to an entire week before rain arrives.
A single cloud usually doesn’t say all that much… but combined with a SEQUENCE of changes in the architecture of the sky you can get a real sense for shifting patterns.
Rain Scenario #1 – Nimbostratus Storms
Nimbostratus storms happen at the warm front of a depression or whenever warm air pushes into and over cold air.
These are often quite large weather systems that take several days to evolve, with the sky going through a gradual series of changes.
Here’s how to recognize a warm front and approach of nimbostratus clouds:
- You start in a period of fair weather.
- This is followed by high cirrus clouds gradually moving in and increasing in thickness and variety.
- Next, altostratus clouds start moving in. These will emerge from the same general direction of the sky as the cirrus clouds.
- Finally, the bottom layer of stratus clouds moves in becoming darker and denser as they completely obscure the sun.
- This darkness continues to intensify until the rain starts. At this point the nimbostratus clouds are overhead.
It’s really that simple!
The entire process sometimes takes days to occur, which means you have lots of warning and time to anticipate the coming rain.
An interesting thing to note is weather systems that take a long time to develop will probably be much larger, last longer, and bring more precipitation.
Other times there are small, fast-moving systems that can develop and move through in less than a day or two.
Rain Scenario #2 – Cumulonimbus Storms
Cumulonimbus clouds happen at the cold front of a depression, or whenever cold air moves in upward drafts that mix with warmer air above.
This is a very different type of rain that develops much more quickly over a period of hours rather than days.
In this case, the series of changes you see in the clouds will start from the bottom of the sky and move towards the top.
- The morning starts out relatively clear & calm. It might just seem like another beautiful sunny day.
- As early morning evolves, you notice small puffs of low-level cumulus clouds floating across the sky.
- As the day heats up, these small puffs start to expand upwards. You start to see increasing signs of active growth caused by thermals.
- Eventually, these clouds become so congested that they begin to expand outwards and upwards at a massive rate.
- When the clouds get large enough, they become cumulonimbus clouds and drop large amounts of rain, with possible hail, thunder & tornadoes in extreme cases.
These storms tend to only last a few hours at most, but can be extremely intense so it’s a good survival skill to recognize the advanced warning signs.
Cumulunimbus clouds form over a few hours, but you can usually detect the early signs of developing rain quite early in the day.
This type of storm tends to be a bit easier for beginners to predict because the changes happen much more rapidly and cumulus clouds are so easy to see.
5 Tips For Learning To Predict Weather With Clouds
Of course, there’s a lot more we could say about predicting weather with clouds, but I hope this article has inspired you to get outside and start watching the sky with a more critical eye.
Here are some practical steps you can take now to begin applying the insights of clouds and hone your newfound weather prediction skills:
- Learn to identify the difference between cumulus and stratus clouds at low, medium, and high levels of altitude.
- Practice watching sequences of cloud changes associated with Nimbostratus storms vs Cumulonimbus storms.
- Keep a cloud and weather journal and track sequences of clouds while testing your accuracy at all times of the year.
- Pay attention to wind speed and direction, then combine your observations of clouds and wind.
- Practice using all your senses to make better observations. Adopt a favorite sit spot in nature and notice what else changes with the birds, plants & overall activity of nature as weather happens.
At the end of the day, weather prediction is a sensory skill that anyone can develop through simple practice & observation.
The best results will always come from combining what you observe about clouds with other clues from nature about upcoming weather changes like:
- Rising humidity will cause your sense of smell to work better with approaching rain.
- Humidity is also easier to sense through the air in your nose than through your skin. Don’t just sniff for scents… pay attention to how the air feels in your nostrils.
- Birds change their behavior and become more active before and after storms. You might notice sudden influxes of rare and vagrant birds being pushed out ahead of a storm system.
- Flowers like dandelions respond to drops in pressure by closing their petals ahead of a storm.
- Morning dew is a common sign of fair weather. If the grass is dry early morning, watch out for rain!
- Each ecosystem has it’s own unique patterns. What is normal for your bioregion? Does weather usually develop quickly or slowly in your area?
This is a huge topic, so let me know what questions you still have about clouds & weather prediction. Most importantly, have fun out there!