• It is the longest day of the year, June 20, and the perfect time to ask the question, “how hot is too hot to hike Grand Canyon?”
• On a nationwide basis, the National Weather Service issues heat warnings at various temperatures for different parts of the country. In general a Heat Advisory is issued for temperatures over 100 degrees for two days, and an Excessive Heat Warning is then temps will be over 105 for the same period, but the numbers vary from region to region.
• There are some unique modifying environmental factors at Grand Canyon. The first is relatively low relative humidity. I have lived in the West for decades, but when I step off an airplane in a hot and humid place, like San Antonio or Bali, I am always shocked by the feeling of almost walking into a wall of heat and humidity. I find that evaporation has very little cooling effect in high humidity. The West, in contrast has a dry heat, sometimes transplants get a front plate for their car that says “dry heat,” maybe because they get tired of explaining to their east coast friends that the temperatures do not feel as extreme as they sound.
• And the evaporative effect can lead to very different strategies when the temperature is 100 and the humidity is 3%, as opposed to somewhere the same temperature with 90% humidity. When I hike in Summer, I like cotton, because it retains water and allows an evaporative cooling effect when you hike. At Grand Canyon, that is desirable, whereas in other parts of the country it is not. The evaporative effect is why the park service encourages you to soak your hat and shirt on a hot hike, and to hop into a stream if you overheat.
• But there are two edges to this environmental sword. If you start a hike on the rim of Grand Canyon, you are as much as mile above sea level, and the atmosphere is thinner. You get as much as a 10% increase in exposure to UV rays for every 1,000 feet of elevation, so on North Rim you may get 80% more UV exposure than at sea level, and on S. Rim you get 68% more. That is why I am so crazy about recommending a floppy hat and a handkerchief of bandana for sun exposure at Grand Canyon.
• There are also multiple strategies that can help in the Canyon heat.
• Loose fitting clothes are an important strategy for me. A thin, loose t-shirt combined with oversized running shorts provide lots of air flow. Wool hoodies seem to be favored in the sun by a younger demographic, but I think I get much better airflow with an ultra-thin, loose, white handkerchief under my hat and protecting my neck. This also serves as an evaporative cooler when I soak the hat and handkerchief in water.
• Starting in the dark also lets you get a jump on the hottest times of day.
• Shade is your friend on a hot day. But it is hard to come by on South Kaibab and Bright Angel Trails. GrandCanyonHikerDude has a useful RU-vid channel, he provides guide services and also posts an online “Shade tracker” at brightangeloutfitters.com/pag...
• The other factor to consider besides the environment is you. Your age, health, experience and acclimation to heat will affect your choices about a hot weather hike.
• So, I promised to provide you with my number, and for rim to rim hikes, it is 100 degrees. I choose not to do a rim to rim hike when the temperature at Phantom Ranch and the deep canyon will be over 100 degrees. Whether you go from the North or South, you will spend several hours in the deep canyon, and temperatures over 100 change the hike from being fun to being work. And even worse than work, the heat can be life threatening.
• Now, I will hike rim to river to rim when the deep Canyon temperatures exceed 100. On Bright Angel Trail, the exposure to the highest temperatures are only on the Devil’s Corkscrew, a section of trail that takes 20 or 30 minutes, depending on your speed and where you define its start and end. With an extra liter of water to pour over my head and body, that period of time is bearable to me, sometimes even fun. After that, the trail hits Garden Creek and a shaded stretch up to Havasupai Garden, so conditions get much better.
• Now, it is true that in Summer Bright Angel Trail is in full sun for much of the day, but as you ascend from Havasupai Garden, temperatures moderate a bit, and if you are lucky there will be a breeze, which aids in evaporative cooling. Even though the South Rim may be hot, it is generally about 20 degrees cooler than the deep Canyon.
• In closing, these are my personal standards and I am also aware of, and accept the risks of injury or death in extreme weather. Also please recognize the Park service says you should never hike rim to river to rim in a day, no matter what the weather, and they say you should stay out of the Canyon on days with temperatures like today. And I am sure they are correct. It is safest to listen to them and their expertise, and not to a crazy guy like me.
22 июн 2024