A favourite activity for nature lovers, hiking is especially popular in summer. Yet heatwave conditions can pose a real danger. Taking the right precautions is essential to enjoy the trails safely. Here's everything you need to know about hiking in the heat.
What are the risks of heat during hiking?
Hiking in extreme heat, particularly during heatwaves, can present 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 disturbances. Without prompt treatment, it can lead to collapse, loss of consciousness, or even death.
In the heat while hiking, the body loses a great deal of water through sweat. If you're not sufficiently hydrated, you risk becoming a victim of dehydration. Symptoms range in severity and typically include intense thirst, unusual fatigue, dizziness or headaches.
Another less common risk is hyponatraemia, linked to 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 genuine threat to your skin. Beyond the discomfort, it can have long-term health consequences, including premature skin ageing and the development of skin cancer.
When to set off to avoid the heat?
To avoid the heat while hiking, we recommend adjusting your schedule in summer. Temperatures typically peak between 12:00 and 16:00, when the sun is at its highest and the atmosphere is at its warmest.
The best strategy to beat the heat is to set off very early and finish the hike before noon. You'll benefit from cooler air, less crowded trails, and significantly reduced chances of feeling unwell.
Another option is to head out in the late afternoon or early evening, provided you have a headlamp and keep an eye on the time to avoid being caught out by nightfall. Either way, outings at these unusual hours are a great way to experience the mountains differently.
If you're on a day hike, don't hesitate to take a break in the shade in the early afternoon to recover and bring your body temperature down before heading off again.
In 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 good physical condition, we suggest postponing your outing for safety.
How to protect yourself from the heat while hiking?
In addition to adjusting your departure time, several strategies can help protect you from the heat while hiking. You should adapt your hike, your equipment, stay well hydrated and protect your skin.
Apply SPF 30 to 50 sunscreen regularly to all sun-exposed areas of your body. Don't forget often-overlooked spots such as the ears, neck and backs of the knees. As well as drinking frequently, feel free 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 while hiking is to plan your route carefully. Prioritise circuits with plenty of shaded areas. In summer, woodland offers perfect protection from the sun. You can also walk near a stream or lake to cool off if needed. Remember to take frequent rest breaks in the shade.
To minimise risk, it's best to adjust your route according to the temperature. Avoid steep elevation gain and intense hikes in favour of gentler walks at a moderate pace.
How to stay properly hydrated while 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 sources along your route. In addition to carrying a good quantity of water while hiking — at least 2 liters — you can bring a filter bottle, purification tablets or a water filter.
Throughout your effort, drink regularly and in small sips. Don't wait until you're thirsty to hydrate. Thirst is already a sign of dehydration. We recommend carrying an easily accessible hydration bladder or water bottle to drink throughout the route.
As for what to drink, stick to water and avoid sugary drinks or alcohol. To prevent hyponatraemia, add a little salt to your water or opt for isotonic drinks or electrolyte tablets. These will help you replenish lost electrolytes.
For a long hike, prepare lightweight meals that are easy to digest. Also pack water-rich snacks (fruit, fruit purées) and fast-acting sugars (dried fruit, cereal bars).
After your hike, make sure to drink mineral-rich beverages, sparkling water or diluted fruit juices. They will support your recovery.
What to wear during a heatwave?
Clothing is an effective way to protect yourself from the heat while 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 absorb it.
Opt for breathable technical t-shirts that cover your shoulders. In cases 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 anti-UV clothing, designed to shield you from the sun's rays.
The bottom half of your outfit should be comfortable and breathable. Wear shorts or lightweight trousers, depending on your exposure to sun, vegetation and ticks. Convertible trousers are a great compromise in summer. In all cases, opt for stretch and breathable fabrics.
To protect your head, hiking caps and hats are essential. Wide-brimmed hats have the added advantage of covering your head, face and neck all at once. Category 3 or 4 sunglasses are also indispensable for protecting your eyes.
Finally, don't forget technical fibre socks. They wick away sweat and reduce friction. Opt for low-cut hiking shoes and avoid waterproof models, which tend to trap heat.
As you'll have gathered, hiking in the heat is perfectly possible — as long as you prepare properly. Adjust your schedule, your kit and your itinerary to make the most of the trails. And in extreme heatwave conditions, don't hesitate to postpone your hike for safety.
