Over the course of a month and a half in Israel, I had a chance to remember what it means to go hiking in hot weather: the constant sweat, the chase after water from the fear of dehydration, remembering to cover my self (or at least use sun screen) and the loss of appetite. All those are pretty obvious things you encounter when hiking in hot weather and we do do our best to be prepared for them, but there are other, hidden, dangers that are too often ignored: heat stroke, sun stroke and overhydration.
Personally I have experienced all the symptoms above in one point or another, feeling the pains of recovery and luckily never reaching any critical point. Most of the time treatment is easy but prevention is the best method – knowing what the dangers are and how to avoid them is better than being always prepared to take care of a problem. I prefer prevention as it means I carry less gear, need less skills (for treatment) and keep myself feeling well and comfortable all the time. Nonetheless, do some extra research on each of the dangers below to know how to treat them as I plan on just describing the danger and how to prevent it, nothing more.
What is hot weather?
What makes weather hot is a personal thing, but in general if you face conditions that are above 95ºF (35ºC), it is going to be hot. Other factors that will influence the situation are humidity levels (high=sodium depletion, low=heat stroke), wind temperature (cool/hot) and strength and cloud cover. Those are general terms of factors that impact hot weather.
Off course, there is always more extreme, especially in deserts, where a combination of high temps (+100ºF/+37ºC), hot wind, low humidity and lack of shade means that hiking is practically impossible during day time and should not be attempted. Is you try to hike in the desert in summer your chances of dying are very high and it can very easily creep up on you. Keep desert hiking for fall/spring (in the winter there is the danger of flash floods).
The dangers of hiking in hot weather
The most famous of hot weather dangers: the body uses sweat to try and cool the body, loosing valuable liquids while not getting enough water to replace it. The blood thickens, reducing oxygen flow so the body starts shutting down functions starting with the saliva in the mouth – which is the first symptom.
The best way to avoid dehydration is staying hydrated – pretty simple but hard to do, especially in very hot weather when you sweat endlessly. If you are able to drink large quantities in one go you don’t need to carry much water with you and can hydrate where possible, but if you can only drink small amounts at a time a big hydration bladder is useful. Always fill your containers every time you reach a water source in hot areas (which are usually dry too) and the rule of thumb is 3-6 litres (6-12 pints) of water per person for a day of walking.
There is the school of thought the believes that you should drink when thirsty, which is great advice, but make sure you have the water when needed. My rule is about 1.5 litres (3 pints) per 1 hour of walking between water sources; for example: I have 17 kms (10.5 miles) between water sources and I know I can walk about 4.5 km/h (2.8 mph) on average so I will carry about 6 litres (12.5 pints) for that section.
Carrying extra containers is useful, I am a great fan of the Platypus collapsible bottles and carry at least 3 containers with me at all times.
The counter of not drinking enough water is drinking too much, a risk that tends to be ignored by inexperienced hikers. The instinct is to think that more water is better, which is generally true when it is hot and you are being active, but there is an important ingredient that is needed with the water: sodium, or salt.
When we sweat, we also release a host of minerals and chemicals to make sure we don’t have high concentration of them in the blood stream; one of the main ones is salt (along with sugar, ammonia, urea, potassium and more). If the weather is very hot and the body temperature is high, we sweat a lot and loose much of those minerals and chemicals that are vital for healthy functioning. High volumes of plain water coming into the body (hydrating) actually diluties those minerals and chemicals and leades to hyponatremia – low sodium levels.
In the long term, the ramifications of hyponatremia are great but for the active hikers they mean one thing in the short run: muscle cramps.
The best way to avoid hyponatremia is to eat salty and sweet snacks regularly – a salty trail mix and a sweet trail mix are the best solution, especially ones that are full of nuts. Adding electrolytes to your water at times is also useful, I use the High5 Zero Tabs (Pink Grapefruit) every 2-3 litres to make sure I add some extra electrolytes to my trail mixes.
Sun stroke is often confused with heat stroke but unlike heat stroke, sun stroke comes from exposure, not internal heat. Sun stroke happens when you ignore all the people around and don’t wear a hat when hiking in the sun – usually a simple point of being stubborn.
When the sun is high and strong, the high exposure and radiating heat can increase the temperature of the body, but more than anything the head. Covering your head and skin can help avoid sun stroke, with the occasional shade and taking breaks out of the sun’s direct radiating heat.
Another good trick is to get your hat wet at any water source to enjoy the cooling effect of the water and the evaporation of the water. I have had sun stroke more times that I’m willing to admit and it is almost always from being stubborn and thinking that my hair can protect me, but it doesn’t. A head cover in direct hot sun is a must and anything will do: hat, scarf, buff, extra shirt or even a piece of cardboard.
The grave mistake many tourists from cold countries make when hiking in a hot country is not putting enough sun screen, or worse, hiking in a sleeveless top. Sun in a hot country like Israel – or any desert area for that matter – is highly radiating, with UV rays just waiting to fry your skin. If you are planning a day in the sun, you must have high factor sun screen (30+ or even 50+) and cover your shoulders – those will burn first, around the backpack’s straps.
Sun burns can and will reach 2nd or even 3rd degree burns and can really painful, but they do heal naturally over time. If you feel the skin starting to warm up too much, pour some cold water or use cold presses (hell, get your whole shirt soaked) and apply more sun screen. Don’t leave for the outdoors without sun screen when hiking in hot weather.
Extra tip: make sure you cover your calves, they tend to burn so fast when you walk in the sun.
The last and most dangerous of all as it is a direct derivative of your choice of recreation: hiking in hot weather. Heat stroke is essentially losing the ability to regulate the heat in the body due to excessive internal heat. When we are active, we produce heat that needs to escape the body and it usually does in the form of sweat or forcing us to slow down due to tiredness. When the body can’t rid of that internal heat any more and doesn’t manage to cool the body, it gets heat stroke and starts “cooking” the internal organs inside the skin.
Heat stroke obviously tends to happen when the environmental heat stress is high and the body can’t catch up with the hot conditions. The best way to avoid a heat stroke (and you really want to avoid it!) is to find external ways to reduce the internal heat and help the body “dump” heat:
- Take breaks only in shaded areas
- When reaching a water source, get in or get you clothes wet to get a cooling effect from the evaporation
- Get your hat wet frequently
- Take more frequent breaks if the weather is hot
- If heat stress is very high, stop in the shade until temperatures reduce
Heat stroke is the reason that most of the Mediterranean is on break from 12-4 pm – it is just too hot to do anything, especially in the peak of summer, and it can be outright dangerous. It was even the reason I didn’t walk the last 7 kms (4.3 miles) of my last hike in Israel.
A general rule of thumb when hiking in hot weather
As a whole, the first symptom of any of those various dangers in the heat is a headache; our brain is a great indicator that something is wrong, especially when it comes to heat.
If your head hurts when hiking in hot weather – stop, find a shady place, drink some water, get yourself cooled down, eat something sweet and salty, drink some more. If the headache is not gone after 15-20 minutes, you have done something wrong in your prevention and an escape route might be needed. Or a longer rest.
Cotton is the source of all evils when it comes to hiking – until you get to go hiking in hot weather, when it is not only allowed but recommended. When it comes to hot weather, all of the cotton’s bad features: hydrophilic (retains water), slow to dry and heavy all become very useful for cooling the body – cotton is almost like an A/C when hiking.
Evaporation leads to energy loss and so heat is “lost” in the process, leading to a cooling sensation on the skin which is very bad when it is cold outside but it is excellent when it is hot. It is good to carry a cotton shirt (not bottom, see below) for hiking or just as a cooling shirt at times. In general, besides the terrible smell, cotton is the best shirt fabric to use when it is hot – just remember to get it wet in every water source.
Chaffing is major issue in hot weather: the constant rubbing from walking (or running) along with the salty sweat and the dust that is part of hot climate areas means that chaffing is inevitable. Here is my set of tools to prevent chaffing when I hike, especially in hot weather:
- Wearing thigh covering, tight, synthetic underwear (you can put it over underwear, too). My favourite are the Under Armour Original Series 9” Boxerjock
- Wipe well after number two’s and always finish with a quick rub of your hand sanitising alcohol – it kills all the bacteria that might linger
- At the end of the day, try and wash up – from a hiker’s shower using bottles to a stream near by – and clean the groin very well with soap
- Apply some Fenistil Gel on any painful spots before going to sleep, they will be gone by the morning
- Put on a fresh pair of underwear and wash (with soap) yesterday’s pair while letting it dry on your backpack during the day. Bonus tip: do the same with your socks
Chaffing is hard to fight but cleanliness, hygiene and staying dry helps – use synthetic underwear, tights and bottoms to stay as dry as possible.
Ready for some hot weather hiking?
Usually lists and advice about hot weather hiking is all about the light colours, covering up, slowing down and resting, but this is not really how I hike so you will not get that advice from me. I like to wear short clothes when it is hot (so I use sun screen SPF 50+), walk as long as there is light and avoid breaks, so this is not the conventional way. To mitigate my style of hiking I choose shaded trails in the summer (where possible) with lots of water sources and carry with me a potential cover (like a tarp), so I can have a refuge from the sun if needed.
The list above is for awareness and a few “how to”s, but you will need to think about your own skills, gear and tools to be able to use the knowledge about those dangers wisely. I like hiking in hot weather sometimes – I like the discomfort and mental and physical challenge and I am always surprised how well I fare: I hydrate well, keep my head covered, love salty snacks and try and cool myself with water and short clothes, which tends to be enough.