CHICOPEE, Mass. (WWLP) - Temperatures are back into the 90s Monday with high humidity. When talking about heat and humidity, we use a term called heat index. The heat index can be compared to what we call wind chill during the winter, it is the real feel of what the temperature is on your skin. Sweat cools your body when it evaporates off your skin. The more humid it is, the more water vapor there is in the air which allows your sweat to evapor…