Climate and crops in northwest Portugal (1798-1830): A glimpse into the past by the light of two Benedictine diaries

This paper aims to assess the impact of hydrometeorological phenomena on agricultural production in northwest Portugal, from the end of the eighteenth century through the first three decades of the nineteenth century. The study analyses and discusses two recently discovered weather diaries from the agricultural region of Entre-Douro-e-Minho, in northwest Portugal (along the Atlantic coast of the Iberian Peninsula, southwest Europe). These written records were kept by Benedictine monastic communities, which used to own large farms in this region. As sources, they provide systematic data concerning weather conditions from 1798 to 1830, along with indications of the impacts on agricultural production in the region. For data analysis, we developed indices for precipitation, temperature, and agricultural production, converting qualitative data into categories of intensity. The results point to important thermal and rainfall anomalies that significantly impacted crops (in terms of yield and harvesting times) and food prices.