The Chilton–Colburn analogy is very helpful for evaluating the heat transfer in internal forced flows. The Chilton–Colburn analogy between the Chilton–Colburn j-factor for heat transfer, j_{H} (St·Pr^{2/3}) and the Fanning friction factor (c_{f}) is popularly considered to hold when St·Pr^{2/3} equals to c_{f}/2, for constant fluid properties. The physical fluid properties, namely, viscosity and thermal conductivity, are generally a function of temperature for microconvective water flow due to a quite steep temperature gradient. Therefore, in present investigation, the validity of Chilton–Colburn analogy between St·Pr^{2/3} and c_{f} is re-examined for laminar microconvective flow with variable thermophysical fluid properties. It is observed that the Chilton–Colburn analogy is valid only for that portion of the flow regime, where St·Pr^{2/3} decreases with decreasing c_{f}. The validity of Chilton–Colburn analogy is also verified by the inverse dependence of Reynolds number (Re) with c_{f}. Two modified nondimensional parameters “*Π*_{Sμ} and *Π*_{Sk}” are emerged from the nondimensional form of 2D, steady-state, incompressible, pure continuum-based, laminar conservation of momentum and energy equations, respectively. These modified nondimensional parameters show the significance of variable fluid properties in momentum transport and energy transport. Additionally, the role of *Π*_{Sμ} and *Π*_{Sk} in flow friction is also investigated. The higher values of *Π*_{Sμ} and *Π*_{Sk} indicate the stronger influence on microconvection due to large variations in fluid properties.