The development of the low-frequency variability (LFV) in the atmosphere at multidecadal timescales is investigated in the context of a low-order coupled ocean-atmosphere model designed to emulate the interaction between the ocean mixed layer (OML) and the atmosphere at midlatitudes, both subject to seasonal variations of the Sun’s radiative input. When no seasonal dependences are present, a LFV is emerging from the chaotic background for sufficiently large wind stress forcing (WSF). The period of this LFV is strongly controlled by the depth of the OML, with a shorter period for a deeper layer. In the seasonally dependent case, a similar LFV is developing that persists throughout the year. Remarkably, the emergence of this LFV occurs for smaller values of the WSF coefficient and is strongly related to the small thickness of the OML in summer, i.e., large impact of the WSF. Potential implications for real-world dynamics are discussed.