When a polymer is used in warm-mix asphalt (WMA) technology, the materials should be heated to a level high enough to maintain its workability because of the high stiffness of the polymer. The styrene–butadiene–styrene (SBS)-modified hot-mix asphalt (HMA) mixtures are produced at approximately 20°C–30°C higher than normal (unmodified) mixtures. If a modified WMA mixture is produced at a lower temperature, the modified WMA mixture will be weaker than the HMA because of the excessive stiffness of the binder at warm temperature. Therefore, using an adequate production temperature [short-term aging (STA) temperature in laboratory] is important for modified WMA mixtures. This study examined STA temperatures of SBS-modified WMA mixtures based on two high-temperature properties [wheel tracking (WT), and deformation strength (SD)], and one ambient-temperature property [indirect tensile strength (ITS)], using four SBS brands. Modified WMA mixtures were prepared in three different STA temperatures (125°C, 135°C, and 145°C). Statistical analyses showed that the three properties of the mixes produced by the STA temperature of 125°C were significantly lower than those of other STA temperatures, at an α = 0.05 level. The STA temperature of 145°C was acceptable for some SBSs, but not for all. Therefore, properties of SBS-modified WMA mixtures were highly dependent upon STA temperatures that significantly affect the workability and compactability. Because modified WMA mixes showed significantly different properties because of the STA temperature, use of proper STA temperatures is very important for WMA mixes to perform properly at high temperature.