The objective of this study was to calculate and analyze the monthly time series of the Heat Index (HI) for Santa Maria, RS, Brazil, during the period from 1968 to 2011. The meteorological variables used in this study were atmospheric pressure, dry-bulb temperature and wet-bulb temperature at 9am (12UTC), 3pm (18UTC) and 9pm (00UTC). Analysis was performed using the highest absolute and the annual average value of the HI. Trends were tested with the Mann-Kendal test and the magnitude of the trend with the linear regression analysis at 95% (α=0.05). At 3pm (18UTC), the historical series of monthly maximum Heat Index in January and April had an increase of 0.76°C decade-1and 0.92°C decade-1, respectively. At 9pm (00UTC), April and November presented an increase of 0.43°C decade-1 e 0.55°C decade-1, respectively. However, May and August showed a decrease of 0.69°C decade-1 and 0.31°C decade-1, respectively.
human discomfort; Mann-Kendall; human health