Standard tables usually assume an ambient air temperature of 30°C (86°F) or a ground temperature of 20°C (68°F). If the surrounding environment is hotter, the cable cannot carry as much current before hitting its thermal limit.
: Excess heat degrades copper and insulation over time. Key Derating Factors
Where:
Where $F_total = F_T \times F_G \times F_S \dots$