The feels-like temperature is derived by taking into account the wind speed and humidity. A living body constantly produces heat and sweats to maintain an ideal internal temperature. Wind cools the body down to the temperature of surrounding air by removing warmer air around its surface. Humidity impedes heat loss through evaporation.
A thermometer does not generate heat internally. Once it has reached the temperature of the environment, it will not cool down further as a fresh mass of air moves across it. It is possible to measure the effect of humidity by surrounding the thermometer with a material soaked in water. Then it will cool down below the temperature of the air until the water has evaporated.
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