Climatological Analysis of the 2022–2023 Unprecedented Dry Period in Southwestern Uruguay

ABSTRACT Uruguay experienced an unprecedented rainfall deficit from June 2022 to May 2023, notable for its magnitude, spatial pattern and socioeconomic impacts, within the context of the 2019–2023 drought that affected southeastern South America. In this study, we conduct a climatological analysis of this period as a case study of a high‐impact climate event, exploring its major features and climate drivers, as well as comparing it with other comparable periods in the historical data record. The occurrence of dry and wet periods in Uruguay is correlated with El Niño‐Southern Oscillation (ENSO) when considering the 12‐month time windows between June to May. While La Niña creates favourable large‐scale and local circulation patterns for reduced rainfall in Uruguay, the largest deficits—including 2022–2023—have not been associated with strong La Niña years, underscoring the complex and multifactorial nature of drought processes. We suggest that various configurations of climate anomaly patterns may lead to prolonged rainfall deficits of similar magnitude but differing spatial distribution across southeastern South America, adding complexity to their analysis and predictability. Differences among the dry periods analysed between 1962 and 2023 could be attributed to the seasonal and subseasonal influences of other climate modes acting together with, and modulating the impacts of ENSO, such as the Southern Annular Mode (SAM), and the Madden–Julian Oscillation (MJO). Additionally, other factors may have contributed to the exceptional 2022–2023 rainfall deficit, particularly surface–atmosphere interactions and land‐use change. Furthermore, although natural variability played a significant role, human‐induced global warming likely exacerbated this exceptional deficit, as reported in previous studies.