ABSTRACT
Temperature is one of the most important of all climate variables for health because of its direct impact on the human body as well as many indirect impacts, such as its effects on disease transmission. Most people have an approximate sense of how hot or cold a given temperature is, but it can be helpful to have a more precise indication of what the temperature might mean in terms of its impacts, or in terms of how hot or cold the temperature feels in the context of the weather conditions. Apparent temperatures measure how hot or cold the air feels: a hot day feels even hotter if it is muggy, and a cold day even colder if it is windy. Heat indices and wind chill factors are examples of apparent temperatures that account for these different perceptions. Various heat indices have been devised to combine temperature and relative humidity, the details of which vary from country to country.
