Net radiation (R_n) is commonly estimated using models that apply the Brunt equation to calculate incoming longwave radiation and use air temperature (T_air) to estimate outgoing longwave radiation under reference conditions. This study evaluated two previously calibrated Brunt models to estimate R_n without site-specific calibration and assessed whether T_air can substitute for canopy temperature (T_c ) under well-watered crop conditions. Measurements were collected in sesame and cotton fields during the first year and in a cotton field during the second year, when T_c was also measured. Net radiation was estimated at hourly and daily time scales. Across all methods, errors were higher at the hourly scale than at the daily scale. Daily-scale performance metrics showed RMSE values of 11.88 and 13.45 W m⁻² and KGE values of 0.91 and 0.74 for the first and second years, respectively. Both regionally calibrated Brunt models outperformed the Allen/FAO method. Although statistical differences were detected between R_n estimates derived from T_air and T_c , regression analyses and error metrics indicated that these differences were small, particularly at the daily scale. Therefore, the calibrated Brunt equations effectively improve R_n estimation, and T_air can reliably replace T_c for daily R_n calculations under well-watered conditions.