Rapid climatic changes and their impact on the geological record is a topic of utmost importance for understanding ongoing global warming and the associated feedback mechanisms on environmental conditions. This study focuses on the Paleocene Eocene Thermal Maximum (PETM), a hyperthermal event characterized by a fast increase in global temperature (5–8°C) over a period of 20 ka. The aim is to understand the chemical weathering response to the PETM and its role as a feedback mechanism for a climatic recovery after the perturbation. Our focus is on the continental section of the sediment routing system near the locality of Esplugafreda in the Southern Pyrenean foreland basin. The changes in the clay mineral assemblages in two size-fractions (<0.5 μm and 0.5-2 μm) were examined as paleoclimatic proxies. Oxygen and hydrogen stable isotope compositions of the clays were measured as indicators of paleo-precipitation, temperature, as well as the paleo-elevation of the catchment. Furthermore, we investigated the Sm-Nd and Lu-Hf radiogenic isotope systems to help constrain the provenance and chemical weathering intensity of the clays. Unlike other weathering proxies, this approach may provide important insights into the pedogenetic processes prevailing in the floodplains and the transported signal to the basin. The clay mineralogy shows an interplay between reworked clays during extreme events, together with more hydrolyzing conditions reflected in the presence of pedogenetic smectites during the onset and body of the PETM. The stable isotope geochemistry supports an increase in temperature with small variations in rainfall intensity over the year, disturbed by extreme events over short time windows. This is evidenced by two negative excursions in the δ18O record before the pre-onset excursion and during the body of the PETM. The ΔεHf results show no variation throughout the profile, indicating no increase in the chemical weathering intensity. Our results suggest that, in this mid-latitude catchment, chemical weathering remained limited by rainfall availability, while physical erosion played a primary control in the sediment routing system due to extreme events under semi-aridic conditions. This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 860383.