When you start sweating the second you exit your pleasant, air-conditioned home, you know it’s humid outside. Whether you’re planning a tropical vacation or hot and humid are conditions you deal with every summer, you need to take extra measures to keep cool and dry. Taking certain precautions can help prevent heat illness, which can be very serious.

Clothing

You wear layers and sweaters when the weather is cold, but it’s not prudent to go the opposite direction and run around naked when it’s hot and humid. The next best option is athletic apparel, most of which is made of synthetic fibers like polyester that wick away moisture. Choose lightweight clothes that are not too tight and avoid dark colors, which absorb more sunlight and heat. Wear a hat and apply sunscreen if you spend an extended period out in the sun. Sandals or water shoes allow for ventilation and tend to dry quickly.

Activity

Avoid too much strenuous activity during the warmest part of the day. Limit your exposure to the sun, and try to spend time in a public, air-conditioned location like a library or mall, especially if your home is not air conditioned. According to the Centers for Disease Control and Prevention, even a few hours spent in air conditioning can help keep your body cool when you return to the hot and humid weather.

Water

Sweat is the release of moisture from your body, so don’t forget to replenish it. Your body needs water to keep cool, so you should drink even if you don’t feel thirsty. Alcohol like beer dehydrates the body, so avoid such beverages. You should also avoid drinks with caffeine or sugar because they actually cause your body to lose more fluid. Water that is at room temperature is best because very cold water can cause stomach cramps -- and you probably have no intention of drinking hot water.

Heat Illness

While you can typically prevent heat illness by following the guidelines for clothing, activity and water, sometimes strenuous activity cannot be avoided -- a sports game outdoors, for instance, might lead to heat exhaustion. Fans might provide comfort because it helps sweat to evaporate, creating a cooling effect, but when temperatures are in the 90s or above, fans are not enough to deal with heat illness. If you feel you might have heat exhaustion, get into a cool environment or into a cold shower. Drink plenty of water and avoid physical activity for the remainder of the day. If you notice someone who becomes unconscious or disoriented, is hyperventilating or has elevated or lowered blood pressure, you should call for emergency medical attention.