In this study, 15 models in the combination, radiation, and temperature‐based groups were evaluated for three consecutive years (2017–2019) with lysimetric measurements in a semi‐arid region of Iran. To investigate the effects of reference plant species and soil textures on the amounts of reference evapotranspiration (ET0), two grass species including Festuca arundianacea Schreb. and Lolium perenne in the three soil textures sandy loam, clay, and silt loam were planted in the weighing lysimeters. ET0 was affected by soil texture and grass species (p < .01). The highest amount of ET0 occurred in the clay soil and Festuca grass. Comparison of the models' results with Lolium grass lysimetric data showed that the minimum and maximum root mean square error (RMSE) values 1.27 and 3.5 mm d−1 were obtained for the Kimberly‐Penman‐1996 (KP) and DeBruin‐Keijman (DK) models, respectively. Regarding the Festuca grass lysimetric data, the minimum RMSE (1.36 mm d−1) was obtained for the KP and the maximum RMSE (3.6 mm d−1) for the DK model. Group comparison of models showed that the combination models performed better than the other groups' models. The estimated ET0 values by the models had a better match with the measured data of Lolium grass than those of the Festuca grass.

In this study, the class A pan coefficient (Kp) values were simulated• The M5 tree model and daily meteorological data used • The Kp value was easily simulated using only relative humidity and wind speed • M5 tree model simulated Kp value with 99% accuracy in all the stations.