Properly Hydrating in the Heat

Properly Hydrating in the Heat

Written By: Samantha McCarthy, MS, RD/LDN


You never know what you are going to get for weather in New England. In the middle of summer, it could be 50 and raining, or we could have a stretch of 90+ degree heat with high humidity. Every summer we have heat waves. It is during these heat waves that hydration becomes a priority. We often donít realize the effects of dehydration until itís too late. Lack of fluids and electrolytes can lead to heat stroke and exhaustion, two conditions you want to avoid at all costs. But, mild dehydration can also affect your day-to-day activities.


Mild dehydration could be as little as 1-2 lbs. Lost in water. This could be from sitting outside in the heat, exercise, or a combination of the two. During the warm summer months, it can easily be achieved. Signs of mild dehydration include:

  • Increased thirst

  • Dry mouth

  • Tired, sleepy, low energy levels

  • Decrease urine output

  • Low urine volume and/or more yellow than normal

  • Headache

  • Dry skin or eyes

  • Dizziness


More severe dehydration is characterized by the following:

  • Severely decreased urine output or no urine output. The urine, if any, produced is concentrated and a deep yellow or amber color.

  • Dizziness or lightheadedness that does not allow the person to stand or walk normally.

  • Blood pressure drops when the person tries to stand after lying down (low blood pressure or orthostatic hypotension)

  • Rapid heart rate

  • Fever

  • Poor skin elasticity (skin slowly sinks back to its normal position when pinched)

  • Lethargy, confusion, or coma

  • Seizure

  • Shock


If you notice any of these symptoms in yourself or someone else, call 911 immediately. To prevent getting to the point of mild or severe dehydration, we need to make sure we drink plenty of fluids.


On a normal day, you should aim to drink half your weight in ounces of water. If you weigh 150 lbs., that means you should drink 75 oz. minimum. For each hour of exercise, add an additional 16 oz. of water. When itís hot and humid out, increase your water intake by at least 16 oz. Amounts will vary person-to-person depending on how much you sweat in the heat. The best thing you can do is monitor the color of your urine. A more clear to pale yellow color means you are drinking enough. If it is a more straw color, you are on your way to dehydration. If you are exercising outside on a hot day, sports drinks with electrolytes are recommended. Throughout the day, also make sure you are consuming lots of fresh fruit and vegetables. These have a higher water content and can help hydrate you. They also contain electrolytes.


Be careful of alcohol intake on hot days. Alcohol causes us to lose even more fluids and can impair our judgement. This can make it difficult to notice any signs and symptoms of dehydration. For every alcoholic beverage you consume, follow it with a glass of water.


So donít overlook the importance of properly hydrating on a hot day. Not only will you feel better by drinking more, you will prevent further complications that could result in severe dehydration.