The increase in solar power generation has a direct impact on the management of the electrical grids, therefore knowing the resource availability for the next few hours and days becomes essential. In this article we present a performance evaluation of the solar predictions provided by the European Centre of Medium-Range Weather Forecasts (ECMWF) in different sites of the Pampa Humeda region, located in southeastern South America. It is found that the intraday hourly rRMSD ranges, on average, between 24.8% and 35.5% depending on the forecast horizon. For the daily integrated values, an increasing rRMSD trend between 16.6% and 21.3% is found for 1 to 3 days ahead, respectively. No significant geographical difference of the performance is observed between the sites. The uncertainty of this forecast model is lower than other numerical weather models previously evaluated in the region, which is consistent with international studies in other regions.