How to read the weather

Read the weather before going on a hike or long trek. 

Knowing how to read the weather during your walking tour helps you enjoy the hill walks more and keeps you safe on the trails.

Why reading the weather during your hike or hill walk is a necessary skill.

Most of you will know the importance of checking the weather forecast before setting out on your hillwalk or hike, no matter the time of year. This knowledge helps you pack the right hiking clothes and other gear into your rucksack before you set out on your outdoor adventure. Being adequately prepared makes for a better hiking experience and means you will be prepared for most eventualities.

But even if you do, the elevation, terrain and temperature changes can lead to weather changes that may catch even the most prepared hiker off guard. These changes may cause a chilly breeze to a 5-minute shower. But be warned, there could be a more nasty surprise around the corner. Therefore, knowing how to read the sky and clouds properly will help you make the right decision and keep you safe for the trail ahead. 

Check the weather forecast.

Daily Forecasts:

To learn how to read the weather, check the local forecast before you head out to learn what rain and storm forecasts will be like on your hike. Ensure that the weather forecast is for the actual location of your trek and not the nearest town or area. Because if you are hillwalking at an altitude, the nearest town could be hundreds of meters lower than your hike, with significantly different weather than your final destination. 

Hourly forecasts:

Analysing an hourly forecast or looking at the rain radar, past and future, will give you a more detailed weather pattern. You will also see the wind speed, direction, and temperature fluctuations. You can use this information as a guideline only as the weather at a higher altitude and on the ridge of a hill or mountain can change quickly and always be unpredictable. It is always best to be prepared for any weather whenever you head out into the hills or mountains.

Talk with the local people who live in the area.

People living in your intended hiking area know and have unique insight into how the weather can turn. The locals also know the weather patterns and what to look for in the current season. This could be the wind patterns, cloud build-up, or other high weather hazards in the hills.

Reading clouds and cloud formations 

How clouds form directly results from atmospheric changes. Therefore when reading the weather they are a great indicator of things to come. You don’t need years of outdoor experience to recognise the most common cloud formations that typically signal weather changes. Let’s say you enjoy a good hike in the Wicklow Mountains with clear blue skies. In the distance, you see an oval, ufo-like cloud hovering over your ascending summit. This lenticular cloud, or clouds, means the wind is building up, and so is the moisture in the air. This could mean that potentially bad weather is anywhere from six to 18 hours away. Knowing this means you will have plenty of time to add a layer of clothing before you get uncomfortable.

Lenticular clouds

lenticular clouds over a mountain. read the weather
Photo by Александр Максин on

They are also known as “Hogs-back” for their distinctive shape, often indicating a powerful system moving in. Combined with strengthening winds, this usually means a storm is approaching within the next 6-24 hours. 

Cirrus clouds

cirrus clouds, how to read the weather, weather in ireland
Photo by Ivan on

Cirrus clouds are high-altitude, wispy clouds. When seen alone, they can be okay. When you see Cirrus clouds combined with low clouds, known as stratus clouds, rain is likely on the way.

Cumulous clouds 

Cumulous clouds are large, white, puffy clouds that indicate fair weather. However, suppose they get taller and have many heads or bumps. In that case, these clouds can bring heavy rain and eventually turn into cumulonimbus clouds that may bring strong winds, hail, thunder and lightning.

read the weather,
Photo by Enrique on

Cumulonimbus clouds

The classic thunderhead is one of the most recognisable and tell-tale signs of a dangerous thunderstorm. Known as “cumulonimbus clouds”, these are flat at the bottom and have huge blooms rising up.

If you see these on your walking tour, you want to turn back or get off the trail and to an exit to make it back to civilisation. Cumulonimbus clouds generally result in heavy rains, lightning, thunderstorms, or possibly tornadoes.

Barometric Pressure

Barometric Pressure is easier to understand than you may think. The average atmospheric pressure at sea level is approximately 29.9 inches of mercury or 1,013 millibars. Barometric pressure drops about one inch of mercury for every 1,000 feet of altitude that is gained or one millibar for every 8 meters that are gained. Therefore bringing an altimeter in your hiking gear is a good idea. Your smartphone, GPS device, or phone may have this function. Suppose you notice a sudden and rapid drop in barometric pressure. To read the weather, you should look up to the skies and beware of any changes in weather during your hike.


When you see lightning, you can estimate the distance by counting de seconds between the flash and when you hear the thunder. Every 5 seconds represent about 1.5 km (1 mile). If you can count to up to 10, the storm is about 10 km or 2 miles away, and you should get down from the ridge or hilltops quickly.

Read the weather for storm indicators.

Weather conditions at lower altitudes are always more clement that on higher ground. Generally, you drop 1 degree C. per 100-meter climb or 3.5 degrees Fahrenheit for every 1000 feet of elevation gain.

This means that a slight drizzle and moderate breeze in the valley could mean a strong wind driving cold rain on the ridge of the mountains or hills. At the same time, you could also find clear skies above the low-lying clouds. It means we are prepared for the worst but can hope for the best. 

Look up and read the sky.

In addition to knowing how to read the clouds and signs of bad weather, looking at the general sky may be a big help in confidently preparing for your hike.

Looking up at clear skies and wispy clouds far away may mean a low-pressure or cold front is on its way. Rain is on its way if moisture is in the air and looks like a ring around the sun or moon.

Reading the sky and understanding what it tells you takes time and practice. When going for a hike or hillwalk, check the weather forecast and look at the sky throughout the day. Review if everything played out as you expected and if what you saw in the sky matched your expectations. This will build your skills and knowledge, and before you know it, you will be able to look up and see if you need to adjust your plans.

Don’t Forget to Prep 

Even if you start your outdoor adventure with a good knowledge of clouds, storms, and cold fronts, this will only benefit you if you take the right hiking gear. Even in the summer, bring a light fleece and waterproof jacket to your hiking backpack.