Thermoforming of cut sheets is extensively used in the industry for various commercial applications. In this process, the sheet is heated to a softened state and subsequently deformed into the mould due to an applied pressure, a vacuum, a moving plug or a combination of these media. The thermoforming-process market is expanding to complex geometries and to a list of potential materials. In this work, I use a no isothermal hybrid approach which combines the dynamic finite element method and the thermodynamic law of perfect gases to study the effect of the temperature of the air flow on the blowing of a thin, isotropic and incompressible thermoplastic membrane. The viscoelastic behaviour of the K-BKZ model is considered. The Lagrangian formulation together with the assumption of the membrane shell theory is used. The numerical validation is performed by comparing the obtained results with the theoretical results for the HDPE grade. Moreover, the effect of the temperature on the thickness and stresses distribution is presented.