During the last two weeks of March 1980 an intense heat wave developed in central and northern Argentina, with its greatest intensity over the city of Buenos Aires. The sequence of temperature anomalies showed the importance of this heat wave. During the period of maximum intensity the daily minimum temperatures were over 27 °C and the apparent temperatures over 30 °C. It was the most intense heat wave of the last two decades and the only one that has occurred in March. The intensity of the event is shown by the high values of several biometeorological indices that indicate dangerous levels of thermal stress on people. The persistence of an anticyclonic circulation at all tropospheric levels and the extension of the barotropic zone to the south led to the maintenance of high values of temperature and humidity. The advective effect added to the intense solar radiation was the most important cause of the high temperatures.