In the Andes the weather is an important factor, the season with the most stable weather is between May and November, which is the recommended season to enjoy our mountains.
However even in these seasons the weather can become unpredictable due to the climate change that has affected the ecosystems, so it is important to be able to read the signs that we have in nature and one of the ways are the clouds, which can help us to prevent a storm or indicate that there will be good weather.

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.
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?

These are the questions you need to ask yourself to understand clouds, clouds that are high medium and low are rain clouds for example, the darker the spots on the clouds the more charged they are, the more they are and the faster they move could be a sign that they may be gathering together to form a storm cloud.

In the Cordillera Real of Bolivia the clouds come from the northeast due to the effect of the cloud forests, the warm air from these clouds colliding with the cold air from the altiplano which can form thunderstorms.

The months of January, February, March are rainy although the temperature is more pleasant, June and July for example are the coldest months of the year and have almost no clouds, unlike many other places in the Bolivian altiplano there is no snow in winter but there is plenty of sunshine during the day and freezing cold at night, August for example is windy while in September the temperatures start to rise.

Bolivia is characterised by a winter season with abundant sunshine and cold nights and a very rainy summer, again due to the contrast of ecological zones, our Amazonas are at 300 m.a.s.l. while the altiplano and the mountains range between 3800 to 4600 m.a.s.l.

Eight Different Types of Clouds That Predict Weather

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.
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.

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.

The most important thing to observe is how big the cumulus cloud is, and whether there are signs of active growth.
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.

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.
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.
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.

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 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!

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.
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.

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.
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.

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.

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.

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.

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.

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

1.- Learn to identify the difference between cumulus and stratus clouds at low, medium, and high levels of altitude.

2.- Practice watching sequences of cloud changes associated with Nimbostratus storms vs Cumulonimbus storms.

3.- Keep a cloud and weather journal and track sequences of clouds while testing your accuracy at all times of the year.

4.- Pay attention to wind speed and direction, then combine your observations of clouds and wind.

5.- 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.

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.