Technical Abstract: Net radiation (Rn) is a key variable for computing reference evapotranspiration and is a driving force in many other physical and biological processes. The procedures outlined in the Food and Agriculture Organization Irrigation and Drainage Paper No. 56 for predicting daily Rn have been widely used. The objectives of this study were to develop two alternative equations to reduce the input data requirements and computation intensity of the FAO 56 Rn procedures to predict daily Rn and to evaluate the performance of these equations in the humid regions of south-east and two arid regions in the U.S. Two equations were developed-- the first equation [measured Rs-based (Rs-M)] required measured maximum and minimum air temperatures (Tmax and Tmin), measured solar radiation (Rs), and inverse relative distance from Earth to Sun (dr) while the second equation [predicted Rs-based (Rs-P)] required Tmax, Tmin, mean relative humidity (RHmean), and predicted Rs. The performance of both equations was evaluated in different locations including humid and arid, and coastal and inland regions (Gainesville, FL; Miami, FL; Tampa, FL; Tifton, GA; Watkinsville, GA; Mobile, AL; Logan, UT; and Bushland, TX). The daily Rn values predicted by the Rs-M equation were in close agreement with those obtained from the FAO 56 Rn in all locations and for all years evaluated. The performance of the Rs-P equation was quite good when compared with the measured Rn in Gainesville, Watkinsville, Logan, and Bushland locations and provided similar or better daily Rn predictions than the FAO 56 Rn procedures. The Rs-P equation was able to explain at least 79% of the variability in Rn predictions using only Tmax, Tmin, and RH data for all locations.