A favourite activity for nature lovers, hiking is hugely popular in summer. Yet heatwave conditions can pose a real danger. It is therefore essential to take the necessary precautions to enjoy the trails safely. Here is everything you need to know about hiking in the heat.
What are the risks of hiking in the heat?
Hiking in extreme heat, particularly during a heatwave, can pose several dangers. The most serious is heatstroke, also known as hyperthermia. It occurs when the body can no longer regulate its temperature and manifests as a high body temperature, severe headaches, nausea, vomiting and behavioural changes. Without prompt treatment, it can lead to collapse, loss of consciousness or even death.
In the heat when hiking, the body loses a lot of water through sweat. If you are not sufficiently hydrated, you risk suffering from dehydration. Symptoms vary in severity and generally include intense thirst, unusual fatigue, dizziness or headaches.
Another less common risk is hyponatraemia, caused by a lack of salt. It can occur when electrolyte losses are not replenished. Although rare, it remains dangerous and can impair brain function.
Finally, sunburn is a real danger for your skin. Beyond the discomfort, it can have long-term health consequences, including premature skin ageing and the development of skin cancer.
When to head out to avoid the heat?
To avoid the heat when hiking, we recommend adjusting your schedule in summer. Temperatures are often at their peak between noon and 4 p.m., when the sun is at its zenith and the atmosphere has had time to warm up.
The best tip for beating the heat is to set off very early and finish the hike before noon. You will benefit from cooler air, less crowded trails and significantly reduce the risk of feeling unwell.
Another option is to set off in the late afternoon or early evening, provided you bring a headlamp and keep an eye on the time so you are not caught out by nightfall. In any case, outings at these unusual hours are a great way to experience the mountains differently.
If you are on a day hike, do not hesitate to take a break in the shade in the early afternoon to recover and bring your body temperature down before heading off again.
During a heatwave, it can sometimes be wiser to cancel your hike. If temperatures exceed 30 or 35 degrees, there are long exposed sections in full sun, or some participants are not in peak physical condition, we suggest postponing your outing for safety.
How to stay cool when hiking in the heat?
As well as adjusting your departure time, there are several other tips for protecting yourself from the heat when hiking. You need to adapt your route, your kit, stay well hydrated and protect your skin.
Apply SPF 30 to 50 sunscreen regularly to all exposed areas of your body. Do not forget often-overlooked spots such as the ears, the neck and the backs of the knees. As well as drinking frequently, do not hesitate to cool yourself down during your hike. For example, dip your forearms or the back of your neck in a stream, or wet your cap, hat or buff.
The best way to protect yourself from the heat when hiking is to plan your route wisely. Opt for a circuit with plenty of shaded areas. In summer, woodland offers the perfect shelter from the sun. You can also walk alongside a stream or lake to cool off if needed. Remember to take plenty of breaks in the shade too.
To avoid taking unnecessary risks, it is better to adjust your route according to the temperature. Avoid high elevation gain and strenuous hikes in favour of more relaxed walks at a moderate pace.
How to stay properly hydrated when hiking?
Good hydration is essential when temperatures are high, especially when hiking. Even before you set off, make sure you drink enough and plan ahead for water points along your route. As well as carrying a sufficient amount of water on your hike — at least 2 liters — you can bring a filtering bottle, purification tablets or a water filter.
Throughout your effort, remember to drink regularly and in small sips. Do not wait until you feel thirsty to hydrate. In fact, thirst is already a sign of dehydration. We therefore recommend carrying a hydration bladder or a bottle that is easy to access so you can drink steadily throughout the route.
As for the type of drink to carry, stick to water and avoid sugary drinks or alcohol. To prevent hyponatraemia, add a pinch of salt to your water or opt for isotonic drinks or electrolyte tablets. These will help you replenish the electrolytes you have lost.
On a long hike, pack light meals that are easy to digest. Also bring water-rich snacks (fruit, fruit compote) and fast-energy options (dried fruit, cereal bars).
After your hike, make sure you drink mineral-rich beverages, sparkling water or diluted fruit juices. They will support your recovery.
What to wear during a heatwave?
Clothing is a great way to protect yourself from the heat when hiking. Garments should be lightweight, breathable and covering to shield you from the sun. Light-coloured fabrics are generally recommended, as they reflect light rather than absorbing it.
Go for breathable technical t-shirts that cover the shoulders. In conditions of strong sun exposure, long sleeves can be a good alternative. Synthetic fabrics or fine merino wool are recommended to wick away perspiration, while cotton should be avoided. For greater protection, you can also choose UV-protective clothing, designed to shield you from the sun's rays.
Your bottom half should be comfortable and breathable. Wear shorts or lightweight trousers depending on your sun exposure, the vegetation and tick risk. Convertible trousers are therefore a great compromise in summer. In all cases, go for stretch, breathable fabrics.
To protect your head, hiking caps and hats are essential. Wide-brimmed hats also have the advantage of covering the head, face and neck all at once. Category 3 or 4 sunglasses are equally indispensable for protecting your eyes.
Finally, do not forget technical fibre socks. They wick sweat away and reduce friction. Go for low-cut hiking shoes and avoid waterproof models, which tend to retain heat.
As you can see, hiking in the heat is entirely possible — as long as you prepare properly. Adjust your schedule, your kit and your route to make the most of the trails. And in extreme heatwave conditions, do not hesitate to postpone your hike for safety's sake.
