How to anticipate the weather

Posted by William, 8th March 2024

Advice to help you enjoy your walking holidays 

The weather can play a major role in our enjoyment of a day's walking, and in some cases can present a real danger, especially in the mountains of the Alps or the UK. Whether you're out for a day's walk near home or on one of our multi-day walking holidays in France or Scotland, it is a good idea to know a bit about different types of weather and the signs that can help you read the skies. 

How to prepare for your walk? 

Always check the weather forecast at regular intervals, ideally in the morning before setting out on your day's walking. In France there are several ways of gaining access to a weather forecast. By phone, the number 08997102 followed by the number of the department (eg 69 for the Rhone) gives you the latest forecast for your local area. If you have access to internet via your phone or a computer then the main site is www.meteofrance.com. Meteo France is the principal agency in France predicting the weather and they provide specific forecasts for the mountains and the coast, as well as providing weather warnings (carte de vigilance) when there are dangerous conditions. If you do not have access to such information during your independent walking holidays, then you can ask your hosts to check for you by asking "Quelle sont les prévisions météo?" 

What are the main dangers from the weather? 

There are many ways in which the weather conditions can upset your day's walking. Here are just a few. A sudden drop in temperature due to an increase in altitude, a sharp wind, the onset of rain or the change in orientation of a slope can cause problems if you are not properly equiped. The wind in its own right can be dangerous. Severe gusts can cause branches to fall in forests or can cause a loss of balance on narrow mountain summits or ridges. Such locations are also hazardous places when a thunder storm strikes. For example our self guided walking holidays in the Queyras region of the French Alps : Queyras Best Kept Secret and Tour of Queyras cross ridges and summits. If you hear a humming noise, the lightning is preparing to strike, and so you need to leave the area as quickly as possible. If the storm has already started, you must not run and avoid stopping under a tree or on an exposed high point. Try to isolate yourself from the ground by sitting on your rucksack. Make sure that there no metal objects in your sack or in your possession. 

Hot, sunny conditions can also cause problems through dehydration and sunburn. This is especially the case in the mountains where even a light covering of cloud is not enough to stop the sun's rays being powerful. 

How to read the clouds? 

Each country, region and even mountain valley has its particularity when it comes to the onset of bad weather, making predictions about the changing weather from how the clouds look or the wind direction is very complicated without an in depth knowledge of the sky and the terrain. For example in the Queyras in the French Alps, which experiences 300 sunny days a year, there is a local weather phenomenon called the Nebbia, which occurs on the eastern part of French alps walking holiday tour. This is when the abundant water vapour given off in the Po basin in Italy rises with the heat and sunshine of the day. From about 10am it starts to condense at altitude and forms thick banks of cloud which roll in against the mountain slopes until they hit the dry air of the Queyras where they dissipate. This occurs in summer on average one in every three days. 

Having said all that, there are certain phenomena which are reasonably common to most parts of France, the Alps and the UK. For example, thunder storms are always linked to cumulonimbus clouds. They start off as small cumulus clouds. Those that stop rising after a short distance are not to be feared, whilst those that build together and rise to cover all three levels of the atmosphere are sure signs of an imminent storm. The top of the cloud shears off in an anvil shape as the upper limit of the cloud hits high winds of the upper atmosphere. 

In France a strong southerly wind accompanied by warm humid weather is a precursor to poor weather arriving from the west. The cloud which arrives for the most part from the west and north west starts off high, but becomes denser and lower as the front approaches. Cirrus clouds are high whispy clouds composed of ice crystals. In France they can accompany fine weather conditions with light westerly and northerly winds. However if they are accompanied by strong persistent winds from the north-east, east or south they announce precipitation in the following 24 hours.