Performance of photovoltaic (PV) modules decreases as the operating temperature increases. This performance drop is typically higher for the crystalline silicon technologies (∼0.5%/°C) as compared to thin film technologies (∼0.2%/°C). The temperature of rooftop modules in hot climatic locations like Arizona could be as high as 95°C depending on the air gap between the modules and roof surface. There are several thermal models existing to predict the temperatures of open-rack PV modules but no comprehensive thermal models have been reported for the rooftop PV modules/arrays based on an extended field monitoring. The primary goal of this work is to quantitatively model the influence of air gap on the temperature of rooftop modules so that the system integrators could improve their designs to maximize the overall energy output (kWh/kW) of the rooftop PV systems. To predict the temperature of rooftop PV modules/arrays based on irradiance, ambient temperature and wind speed conditions, this paper presents five thermal models for each of the five air gaps (0, 1, 2, 3 & 4 inches) investigated in this work.