Weather
Check the weather forecast, it's not always blisteringly hot in the summer, there are cool days and breezy days. Hiking in the summer rain can be quite refreshing! Plan your trips for days that are going to be more enjoyable. The weatherman doesn't always get it right, but having an idea of trending weather patterns is very helpful in avoiding the heat.
Time of Day
The time of day makes a huge difference as to how warm it gets. Early morning hikes are certainly cooler, but head out in the heat of the afternoon and you'll be exerting yourself in the hottest part of the day. Of course, it usually tends to cool down towards evening most days. Consider late afternoon departures and returns after dark. Some of my best hiking experiences have been enjoyed via headlamp in the cool night air.
Elevation
As experienced hikers know, it's always cooler in the mountains. The higher the elevation, the less dense the air is, and the less heat capacity it has. That is, it's cooler the higher up you go. The caveat here is that sometimes the sun's rays can be stronger as the atmosphere thins. So keep up with the sunscreen and keep covered.Plan Your Destination
If you know it's going to be warm, choose a trail that is densely covered with shade. Hiking along a cool shady path in the middle of a hot day is the epitome of beating the heat! Foliage can have a big impact on the ambient temperature as well. Hiking along a stream or near a lake can also help keep you cool as the presence of water has a moderating effect on temps. Another favorite trick is to head out where the shadows are long from a local mountain and avoid the sun for hours at a time.
Base Layer
A base layer is the clothing that you put directly against your skin, either as the only layer or as an underpinning for you outer clothes. It's critical that this layer is a wicking material, that is, it pulls moisture away from your skin. Choose materials that are designed to keep you cool and dry, like Merino wool or a good synthetic. Whatever you choose, you want the moisture from your body's exertion to be pulled away from your skin to evaporate so that you are cooled as you sweat. Don't wear cotton next to your skin because it gets wet and stays wet, making you feel hot and sweaty. You are also much more likely to chaff and blister wearing wet cotton.
Outer Clothing
The lighter the color of your clothing, the cooler you'll stay. Lighter colors reflect the sun's rays, darker colors absorb them. Also, keeping covered can help keep you cool! This seems counter intuitive, but if you look at the clothes people wear in extremely hot areas of the world, it's all about coverage and a loose fit. You're much less likely to burn as well, if you are more covered. You want your outer layers to be of a lightweight, breathable fabric that has a good SPF (sun protection factor). Wear a hat, and keep the sun off your head, wide brims are better protection than a ball-cap.
Listen to Your Body
Studies have proven that your body is very self regulating, to the point that it will slow you down, and even stop you from exerting yourself if it gets too hot. Have you ever noticed how you feel slow and lethargic on the hottest of days? That's your body telling you it's probably too warm to start getting physical. Even starting out a hike in warmer weather, your will likely feel more sluggish as your body anticipates getting warmer due to muscle exertion. Take more frequent breaks and listen to your body telling you it's starting to get too warm.
Heat Adaptation
Scientific evidence shows that if you exercise in the heat, your body will begin to adapt and you'll become more efficient within about 5 days. It actually takes about 2 week to fully adapt, but the rate of heat adaption is significantly more rapid in the first 5 days of exposure to warmer temperatures. Give yourself a chance to adapt to the heat before really pushing yourself.Hydration, Hydration, Hydration
When you exercise in the heat, you sweat, a lot! Water is the lubrication that keeps your human machine running efficiently. You need to keep your body hydrated, that is, you need to drink water to replace the water that is evaporating off of you as your body attempts to cool itself. It's recommended to drink at least a litre (16oz) over the couple hours before you hit the trail, and then a cup (250ml) of water, at least, for every 15 minutes of exertion during your hike. If you're sweating, you're not just using up your body's water reserves, you are also consuming the salts that help balance your body's internal blood pressure and nervous system. These salts are called electrolytes and you need to replenish them as you hydrate too. Have a good snack on the trail or even add a small amount of Gatorade powder to your water bottle to keep your body happy.
Tip: Dip Your Feet!
There is almost nothing better in this world than, after, a long hot hike, finding a stream or lake, taking off your boots and socks and dipping your feet and ankles in the cold refreshing water. You have to try it if you haven't ever. There is nothing like it, and it is my absolute favorite way to beat the heat while hiking in the summer.
