The fall armyworm (FAW) is of tropical–subtropical origin and defined as one of the most destructive agricultural pests globally, including Egypt. This study aims to effect of temperature factor on the biological cycle and generations of Spodoptera frugiperda under laboratory conditions. The highest mortality occurred when the caterpillars were kept at 32°C in the F2 generation. In general, among the temperatures tested, 24 °C and 28 °C promoted the greatest number of days in incubation. The average duration of insect development in days was inversely proportional to the increase in temperature. Understanding the climate factors are necessary to clarify the possible influences of global climate change, including warming on this species, in addition to evaluating the adaptation of insects over generations.