Ultrathin composites offer numerous advantages relative to conventional composites owing to its higher strength-to-weight ratios. Employing ultrathin composites is substantially beneficial for aerospace structural applications on account of the extensive constraints imposed on weight in these applications. However, imperfections in these composites can lead to a significant drop in their structural performance. Lower service temperature may lead to aggravated thermal strains or stresses and therefore further increase the structural imperfections and reduce structural performance. This paper studies the effects of imperfections on the critical buckling load of ultrathin composite cylindrical shells subjected to compressive loads and under cold temperatures. The imperfections explored include ply angle and ply thickness imperfections. The effects of modeling the imperfection as spatially uniform are investigated here. Studies are also carried out on the variation of critical buckling load of the imperfection seeded cylindrical shells at different temperatures as well. A numerical framework was designed to efficiently carry out the simulations. The results indicate that the influence of intrinsic imperfections on the critical buckling load is more dominant relative to temperature induced variations when imperfections are modeled as spatially uniform.