THE WEATHER IN PORTUGAL BETWEEN 3 AND 6 DECEMBER 1739 (BASED ON DESCRIPTIVE DOCUMENTAL SOURCES). Instrument-based meteorological observations in mainland Portugal started to be gathered in the 1770s. Weather in Portugal before that time can therefore only be reconstructed based on descriptive documental sources in which generally only extreme weather events are recorded. Due to the subjectivity of this type of information, critical analysis of the sources, their diversity and data crossing prove essential in order to be able to assess their trust-worthiness. Here we have chosen to analyse a gale that swept across much of mainland Portugal between 3 and 6 December 1739. The violent winds coming from the South, which according to reports may have reached speeds of 120km/h, were accompanied by heavy, continuous rain that produced flooding in the basins of the rivers Tagus, Mondego and Douro. Large-scale damage would have occurred, backed up by references to the death of many animals and the loss of human lives. As nowadays, these storm events were originated from winds coming from the South
