The “heaviest rains that man had ever seen or heard of:” interpreting a weather event in late medieval Portugal

The fifteenth-century royal chronicler Fernão Lopes describes a weather event on 24 October 1384 in which the future King João I of Portugal (1385–1433) failed to attack a strategic castle because of a tremendous storm that caused the army to lose its way in the dark and rendered the roads and river crossings impassable. The city of Lisbon flooded and there was considerable damage to buildings. The description of the storm and its aftermath is by far the longest description of weather for medieval Portugal. The aim here is to set this storm within the context of the late medieval crisis, placing it alongside the warfare, plague, papal schism, siege and hunger also described by Lopes, and exploring it in relation to research on late medieval climate change. Lopes’s chronicles are major sources for crisis in medieval Portugal, but this storm has not previously been considered within that context.