Data for: Streit J.O., Invernizzi M., Bottaro S., Tamiola K., Lindorff-Larsen K. (2026). Transient tertiary structure in intrinsically disordered proteins revealed by multithermal enhanced sampling. bioRxiv Content: OPES_multiT contains all OPES multithermal simulation data of AAQAA3, fragment ACTR (ACTR residues 20-60), ACTR, and HTTex1 16Q. All input files, processed trajectory files and calculated properties are included. Simulations were performed with GROMACS 2023.4 and PLUMED 2.10. The subdirectories containing "PRODUCTION" in their name is where the main MD simulation data is stored. The total aggregate simulation times of these systems was 15, 25, 25, and 20 microseconds, respectively. Ensemble_reweighting contains experimental data (NMR and SAXS, exp_data_ACTR subdirectory) and ensembles of ACTR (from OPES multiT and REST2 simulations). The ensembles were reweighted using the BME code (https://github.com/KULL-Centre/BME) and cross-validated against left-out data. The ensembles are contained in the ACTR_* subdirectories. Reweighting data and analyses are included in the opes_* and rest2_* subdirectories. The subdirectory "potenci" contains random coil chemical shifts used to calculate secondary chemical shifts. The main ensemble analysed in the paper ("ACTR_OPES_310K_ensemble"), which was reweighted with chemical shift (CS) and paramagnetic relaxation enhancement (PRE) NMR data is divided into 5 XTC files (traj0-5.xtc). PREframes.txt correspond to the final frame indices included in the ensemble, and CS_PRE_rew_weights.txt contains the final weights of these frames after BME reweighting. Additional calculated properties of the ensemble are also included.