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Understanding the Feels-Like Temperature: Wind Chill and Heat Index

On a bright February day, you might turn on your television to check the weather. The forecast shows an air temperature of 30 degrees Fahrenheit, which might seem manageable during winter. However, you quickly realize that the “feels-like” temperature registers at 20 degrees. At that moment, the thought of a warm beverage and a cozy hat becomes very appealing.

This “feels-like” temperature is influenced by factors such as wind chill or humidity, and similar experiences can occur during the sweltering days of summer. High humidity at an 80-degree temperature can make it feel like a stifling 90 degrees.

According to meteorologist Cyrena Arnold, the feels-like temperature essentially reflects how temperature impacts our skin. “Our skin features sensors and retains water, which influences its behavior regarding moisture evaporation,” she explains.

Feels-Like: Wind Chill

Cold air combined with brisk winds can enhance the sensation of cold significantly. Rapid air movement accelerates heat loss from the body, leading to quicker evaporation of moisture from the skin.

“For moisture to evaporate from your skin, it requires heat,” Arnold states. “Wind chill can expedite this process because the cold air enhances the evaporation rate while drawing away body heat.”

This accelerated evaporation is why outdoor enthusiasts like hikers or skiers should avoid wearing cotton fabrics, which can worsen the chill.

[ Related: Why 60 Degrees in Fall Feels Different from Spring. ]

“Cotton promotes rapid moisture evaporation. In contrast, wool and synthetic materials retain warmth better, which is critical in cold conditions,” Arnold elaborates.

Meteorologists utilize a mathematical formula to determine wind chill, alongside visual charts that offer a quick reference.

CREDIT: National Weather Service/NOAA.

Feels-Like: Heat Index

The phrase “it’s not the heat, it’s the humidity” rings true. Sweating is the body’s natural mechanism for cooling off, but high humidity levels hinder this process. When moisture saturates the air, it becomes increasingly difficult for sweat to evaporate.

Arnold notes, “Excess humidity prevents adequate evaporation, inhibiting the body’s cooling system. Consequently, high humidity coupled with heat can make conditions feel oppressive.”

Meteorologists apply a formula to calculate the heat index as well.

CREDIT: National Weather Service/NOAA.

Managing Heat and Cold Challenges

Navigating the effects of feels-like temperatures requires strategic planning, particularly to avoid severe conditions like heat stroke or frostbite. When heat indexes soar, engaging in vigorous activity can be risky, making it vital to adapt outdoor plans accordingly and find shaded areas when possible. In the summer months, wearing light-colored cotton clothing can facilitate the evaporative process.

“A white cotton t-shirt is an excellent choice in summer, as it aids in cooling while you sweat,” Arnold advises.

Staying properly hydrated is essential as the body works tirelessly to regulate temperature through perspiration, especially in the heat.

Conversely, during colder months, it is crucial to wear loose-fitting insulating layers. Tight clothing impedes the ability to trap warm air.

“Wearing multiple layers is beneficial, but they need to fit loosely to allow air pockets to form for insulation,” Arnold explains.

Ensuring that exposed areas like cheeks and ears are covered is vital for those spending significant time outdoors, as frostbite can occur in less than 10 minutes.

Arnold shares a piece of advice: “There’s no such thing as bad weather, only inadequate gear. With the right preparation and technology, we can endure both extreme heat and cold.”

This piece is part of a series that addresses various inquiries regarding weather phenomena, inviting questions from readers to expand the conversation. Submit your questions.