How to respond to sudden changes in the weather in the mountains: a practical guide for walkers

The mountains are unpredictable. Even during the summer months, when conditions seem stable and favourable for enjoying a walk, the weather can change in a matter of minutes.

Thunderstorms, strong gusts of wind, thick fog or sudden drops in temperature are more common than many walkers realise.

Knowing how to interpret the signs in your surroundings and what to do can make the difference between a minor incident and a dangerous situation.

Why do conditions in the mountains change so quickly?

The mountainous terrain encourages the formation of local weather phenomena that are difficult to predict accurately. During the summer, daytime thunderstorms are particularly common, caused by the ground heating up throughout the day.

As the warm air rises, it can form clouds with significant vertical development (cumulonimbus clouds) capable of producing heavy rain, hail, lightning and even strong downdrafts.

Furthermore, the temperature drops by approximately 0.6 °C for every 100 metres of ascent, so a pleasant day in the valley can quickly turn into a cold and damp environment at higher altitudes.

Before setting off: prevention is the best approach

The best way to deal with a sudden change in the weather is to plan ahead.

Before starting any route, it is advisable to:

• Check the specific mountain weather forecast via official sources.
• Check weather warnings for storms, strong winds or high temperatures.
• Study the route and identify possible shelters or escape routes.
• Inform family or friends of your planned route and approximate time of return.
• Adapt the activity to the group’s physical and technical ability.

It is worth remembering that general forecasts for nearby towns do not always reflect the actual conditions that may prevail in mountainous areas.

Signs indicating deteriorating weather

During the activity, it is important to remain alert to certain indicators:

Rapid development of vertical cloud cover

The appearance of large anvil-shaped clouds or the rapid growth of cumulus clouds may indicate the formation of storms.

Sudden increase in wind

Abrupt changes in wind strength or direction often precede the arrival of storm fronts.

Sharp drop in temperature

A rapid drop of several degrees may signal imminent rainfall.

Distant thunder

If you hear thunder, even if it seems distant, you should assume there is a risk of lightning. The general rule is simple: if you can hear the thunder, you are close enough for lightning to pose a danger.

What to do in the event of a thunderstorm

Thunderstorms represent one of the greatest risks in the mountains.

If a storm is approaching:

• Leave ridges, peaks and exposed areas immediatelyAvoid staying near isolated trees, masts, metal crossings or via ferratas.
• Stay away from watercourses and wet surfaces.
• Keep walking poles, ice axes or other metal objects away from your body.
• If the group is large, spread out its members several metres apart to minimise the impact in the event of a strike.
• Seek shelter in enclosed buildings or vehicles if available.

If there is no suitable shelter, adopt the safety position: crouch down, with your feet together on a rucksack or insulating material, and minimise contact with the ground. Never lie flat on your back.

Fog: when navigation becomes difficult

Fog can drastically reduce visibility and make navigation difficult.

In these circumstances:

• Slow down your pace.
• Use a GPS, map and compass to constantly check your position.
• Follow signposted paths only.
• Avoid taking impromptu shortcuts.
• If there are reasonable doubts about the correct route, the safest course of action is to retrace your steps to the last known point.

Hypothermia and cooling in summer

Although many people associate hypothermia exclusively with winter, it can also occur in summer due to a combination of rain, wind and exhaustion.

Some early symptoms include:

• Persistent shivering.
• Clumsiness.
• Difficulty speaking clearly.
• Severe fatigue.
• Disorientation.

If you experience these signs, it is essential to change out of wet clothing into dry clothes, shelter from the wind and, if possible, consume hot food and drink.

The right kit makes all the difference

Proper planning of your kit is essential for dealing with unexpected changes in the weather.

On any trip to the mountains, you should take:

• A waterproof and breathable jacket.
• A lightweight thermal layer, even in summer.
• Sun protection (cap, sunglasses and sun cream).
• Sufficient water and food.
• Head torch with fully charged batteries.
• Basic first-aid kit.
• Mobile phone with sufficient battery life or a power bank.
• Map or GPS device.

Furthermore, wearing suitable footwear, offering good stability, protection and grip, helps you proceed more safely when the terrain becomes slippery or conditions deteriorate.

Sometimes the best decision is to turn back

In the mountains, reaching the summit shouldn’t always be the main objective. Recognising when conditions are no longer safe and deciding to turn back is part of responsible hiking.

The experience isn’t just about getting there, but about returning home safely so you can continue to enjoy new adventures.

Because the best route will always be the one that ends well.