Catalogue and Analysis of Extraordinary Precipitation Events in the Spanish Mainland, 1916–2022

Catalogues of past hazardous events are essential for understanding their magnitude, frequency, geographical distribution and underlying mechanisms. Such compilations provide critical data for identifying patterns, improving predictive models, and enhancing preparedness, thereby contributing to the mitigation of future risks and facilitating effective adaptation to climate-related hazards. In this article, we present the first comprehensive catalogue of extraordinary precipitation over the Spanish mainland, spanning more than a century. This work provides valuable insights into spatial and temporal patterns of these events. We compiled monthly maxima of daily precipitation (Rx1day) exceeding 100 and 200 mm by combining the documentary collections of the AEMET National Climate Data Bank (1916–2022) with newly digitised data from the Annual Summaries of Observation Books (1916–1950). As a result, this dataset represents the most extensive and detailed collection of extraordinary precipitation events in the region. It includes 19,184 monthly maxima records above 100 mm from 4325 observatories, occurring across 4814 days (events). Additionally, there are 1130 records exceeding 200 mm, grouped into 530 days and recorded in 664 observatories. As anticipated, extraordinary rainfalls were most frequent in autumn, while summer recorded the lowest number of events. These events occurred across nearly all regions, although a higher concentration were observed near coastlines. This is particularly the case of records and events over 200 mm, which concentrated along the Mediterranean arc. We identified five spatial patterns that correspond with specific weather types. Beyond atmospheric circulation, the topography played a critical role in determining the spatial extension of extraordinary precipitations. The newly digitised dataset is available at https://digital.csic.es/handle/10261/354840, accompanied by a collection of maps of daily events. Raw data from the AEMET's National Climate Data Bank are subject to a licenced agreement.