Surface and upper‐level wind speed changes were analysed for several weather stations distributed throughout Argentina from 1990 to 2020. Both annual and seasonal wind speed trends were estimated for individual surface stations and available rawinsonde data. In order to explore the nature of these changes, different percentile time series were evaluated. NCEP/NCAR and ERA5 data were also assessed to verify how these long‐term changes are represented by the different reanalysis time series. A significant decline in measured surface wind speed is observed for most stations, with a reduction up to 13%·decade−1 in some of them. Despite differences on each station's wind speed distributions due to regional characteristics, the estimated trends were mostly negative for the annual 75th and 95th percentile time series. Upper‐level stations registered positive trends especially in the upper troposphere (200 hPa) in northern Argentina, while Patagonia's wind profile showed significant positive wind speed trends at most levels. Reanalysis data have severe limitations to reproduce the observed behaviour in the near‐surface levels, but managed to generate adequate estimates for the medium to high troposphere.

Reference evapotranspiration (ETo) is a variable used to characterize the evaporative demand of the atmosphere and its impact on the water balance. During the last decades, significant ETo variabilities have been observed, especially at mid‐latitudes. These variabilities respond mainly to local variations in their physical drivers, such as solar radiation, vapour pressure deficit or wind speed. In this study, the annual and seasonal ETo estimates are generated using the Penman–Monteith method (FAO). Surface weather stations for the Argentine territory and reanalysis data for southern South America of the last four decades (1981–2020) are used. Contributions of both aerodynamic (ETaero) and radiative (ETrad) effects are evaluated to analyse their driving role. Significant positive ETo trends are observed from reanalysis data throughout Argentina, especially on the central east side of the Andes Mountain range with values up to 10 mm·year−1. Most of these ETo changes respond to positive trends in air temperature in the study area, while those in the central Andes also respond to negative trends in dew point temperatures. On the other hand, the increase in energy availability through positive trends in net surface radiation produced a slightly higher ETo in the northern regions of the country. Regional ETo values have shown to be more sensitive to variations in air temperature in the northeastern areas, although changes in humidity and solar radiation could also play a role. In a context of climate change, given that temperature and rainfall are expected to increase in the central and northeastern region of the country and decrease along the eastern side of the Andes Mountains in the coming decades, the characteristics observed over the 1981–2020 period are expected to intensify in the near future.