Hydration Matters, No Matter the Weather

We all know how important it is to stay hydrated when it’s hot and/or humid outside, but why? And why is it that we feel so dehydrated when we go hiking or skiing out west in dry and/or cold weather?


Maintaining a consistent core temperature (between 97°-99° F for most humans) is one of your body’s key jobs. If your core temperature gets even 1.5° higher (or lower) than normal, it can make you feel really awful – think headaches, dizziness, nausea, and other fever/hypothermia symptoms. 

Blood is the key element to temperature control. Warm blood (warmed up in the torso by passing through and around organs with high metabolic processes – giving off lots of heat) can be passed around to help warm us up. Cooled blood (from traveling to the surface of skin can help cool us down). 


The primary system though for cooling off our bodies, especially in hot weather, is evaporative cooling. Evaporative cooling works by the body shunting blood to the surface, and pushing out sweat (which comes from blood plasma) through the pores in our skin. From there, ideally, the sweat evaporates off our body and cools us down.

Since sweat comes from blood plasma, it decreases our blood volume – it’s critical to replace that fluid through consuming liquids.

When it’s humid, however, this evaporative cooling system doesn’t work very well anymore. Instead of switching to a different system, the body will produce more and more sweat, in an attempt to make it work. The body doesn’t know that the local weatherman said it was 100% humidity outside, it just knows it needs to get the core temperature down, and sweating is the only way it can make that happen. This is why in hot & humid climates, we can get so dehydrated so quickly.


Oddly enough, the same rapid dehydration occurs in dry, especially cold and dry climates. What? How is it that in the opposite environment, we have the same problem? Dry air evaporates moisture faster than humid air. Our body’s water vapor from breath, moisture in skin, and sinuses evaporate the same way sweat does.

When it’s hot and dry, we sweat just as much as when it’s hot and humid – it simply evaporates off of the skin faster. But because we don’t tend to notice the heat as much, we don’t tend to remember to replenish liquids.

In cold weather, the body’s thirst signals are not triggered as easily, so we tend to drink less water. The air tends to be drier in cold weather, and again, we often don’t notice our sweat under thick, heavy clothes. Just like proper hydration is important for keeping us cool in hot weather, proper hydration is critical for keeping us warm in cold weather. We need sufficient blood plasma to circulate blood to our extremities, and hydrate cells for proper function (i.e. metabolic processes that can produce heat). If you often find yourself too cold in the winter, try drinking more water!


So, we have determined that no matter what the weather is, it’s important to stay hydrated. But how do you know if you’re dehydrated? Symptoms of dehydration include headaches, fatigue, dry mouth, lightheadedness, and dark urine (any darker yellow than lemonade color). Further signs of dehydration or heat injury include ceasing to sweat when it’s hot out and nausea or vomiting. In most cases of dehydration, before any heat injury symptoms begin, replenishing with water is the best place to start – and drinking water often! The common recommendation is to drink around 2 litres or 8 glasses of water daily – not taking in to account body size, hot weather, or exercise.

What if you drink tons of water, your urine is clear, and you still feel symptoms of dehydration? What if it seems like every glass or bottle of water simply passes through your body and you’re having to visit the restroom 30-40 minutes later, especially with nearly clear urine? These cases are likely signs that your body doesn’t have sufficient electrolytes.


Many of us have heard of electrolytes – they’re in popular drinks like Gatorade or Powerade, and they’re important for athletes. Well – there’s a little more to it. Electrolytes are different types of salts that bond to water molecules to transport them into blood (and then to any cell in the body, or even to transport water out of the body as sweat) – think of them as Uber for water molecules! Without these salts (electrolytes), the water you drink can’t be transported.

We’re using the term “salt” a lot – but electrolytes are much more than table salt that you add to your french fries. Yes, sodium (Na) is an important electrolyte, but as are potassium (K), Calcium (Ca), Magnesium (Mg), and Chlorine (Cl). There are others, but these 5 are the primary electrolytes in the body chemistry. Electrolytes are found in common foods and can be replaced that way, but also can be replaced using drink mixes developed for sport, which are especially handy in very hot and/or humid weather, or during exercise. 

One of Anna’s favorite electrolyte replacement tools for daily use is Emergen-C packets – a great way to start summer days (and easily found at Target/Walmart/Walgreens/CVS). Body Armour is a nice alternative, though it’s higher in sugar. For sports or heavier replacement, her favorite product is Torq Nutrition (which is a local Roswell, GA company) – companies such as this one, Skratch Labs, and Sword Nutrition, focus on using real foods to create their electrolyte mixes, leaving them lower in sugar and lighter in flavor, and easier on the stomach. 

Gatorade and Powerade are good choices, particularly if you’re doing exercise and can use the carbs – we prefer the G2 Gatorade (which is about half the sugar with the same electrolyte content).

In summary, be sure to stay on top of hydration all year round, even if you’re inside, it’s cold, or it’s dry. It’s especially important in any extreme climates such as very dry, very humid, very hot, or very cold. In the office, we love to tote around gallon-sized water jugs as a companion to our regular drinking glasses or reusable water bottles. These jugs are a quick refill source, and an easy way to visually track water intake. Stay hydrated! Your cells will thank you!