The studies developed in the context of Biometeorology and Human Bioclimatology show some of the effects that weather and climate can cause on human being. The application of these biometeorological indices, allows to identify some of the combined effects that different climatic elements can cause on people's health and comfort.

These indices make use of theoretical models to quantify the biometeorological human comfort.

There are several indices used in several worldwide meteorological services (WMO, 1972; Steadman, 1984; Steadman, 1979; Kalkstein et al., 1996).

Currently, the Portuguese Meteorological Institute (IM, I.P.) uses two distinct indices to monitor biometeorological conditions: