CubeSats are attracting significant interest as an enabler of easy access to space due to advantages in low development costs and shorter development times compared to traditional satellites. The CubeSats operating conditions are determined by solar, albedo, and Earth infrared radiation. However, the amount of heat radiation is not constant and instead depends on the orbital parameters and satellite altitude. This unsteady radiative condition will affect a CubeSat’s operating system, including electronic devices. To ensure that the operating temperature of these devices does not exceed the safe limits, thermal analysis based on the temperature ranges of the CubeSat structure along the satellite orbit is crucial. Therefore, the aim of this study is to estimate the temperature ranges experienced by a CubeSat’s structure, which includes the primary structure and main electronic components operating under various duty cycles. Specifically, the worst hot and cold conditions are computed for Australia’s Waratah Seed Ride-Share mission flight conditions using numerical simulation. The energy radiations from direct solar, albedo, and Earth infrared are considered as the main energy sources for the CubeSat and computed according to the orbit trajectory. Furthermore, various materials of the primary structure are selected to investigate the effect of the selected materials on the operating temperature ranges for the electronic systems in the worst hot and cold conditions. Finally, the results from various conditions regarding the temperatures and structure’s materials are compared and presented in this study.