Characterising Vento Norte Downslope Windstorms and Their Thermal Impacts in Southern Brazil

ABSTRACT

This study investigates the meteorological characteristics and associated human thermal discomfort of downslope windstorms known as ‘Vento Norte’ (VNOR; ‘North Wind’ in Portuguese) occurring in the city of Santa Maria, southern Brazil, over 20 years (2004–2023). VNOR events are characterized by unseasonable strong northerly winds, abrupt temperature rises and significant drops in relative humidity. Utilising hourly meteorological data, we identified 189 VNOR episodes, predominantly occurring during austral winter months (June–August), reflecting a seasonal pattern. VNOR events significantly altered local thermal comfort conditions, as demonstrated through a comparative analysis of five biometeorological indices: Effective Temperature with Wind (TEFW), Thermal Discomfort Index (TDI), Temperature–Humidity Index (THI), Human Discomfort Index (HDI) and Humidex (HU). Statistical analyses revealed significant differences between VNOR and non‐VNOR periods, with VNOR episodes consistently associated with elevated human thermal discomfort. A detailed examination of representative events further illustrated abrupt changes in meteorological parameters, highlighting the potential for rapid thermal stress in the local population. The present analysis demonstrates the importance of monitoring VNOR phenomena and their thermal impacts and suggests how these downslope windstorms alter local atmospheric conditions, providing an environmental baseline that could support future risk‐awareness frameworks and biometeorological monitoring protocols in southern Brazil.