Thermal stratiﬁcation can lead to the damping of turbulence, which reduces the mixing of solutes in a ﬂuid body, and in turn, aﬀects river health. A series of Direct Numerical Simulation (DNS) solutions sweeping through a range of four diﬀerent channel radius of curvature is obtained to investigate the eﬀect of curvature on stratiﬁcation in meandering thermally stratiﬁed turbulent open channel ﬂow. This range of radius of curvature will cover a range of the curvature parameter 0.2 < γ <1.5, which is typical of rivers in the sharp to mild curvature range. Here γ = C_f^-{1} (H/R_{min} is a dominant control parameter with respect to velocity redistribution in curved open-channel ﬂow, where C_f is the Chezy friction coeﬃcient, R_{min} the minimum radius of curvature, which occurs at the meander apex, H the meander height. An internal heat source models radiative heating from above following an exponential Beer’s law proﬁle, which varies with height due to progressive absorption. Based on the DNS results, the present paper addresses two issues. Firstly, the inﬂuence of changing curvature on the complex tri-cellular pattern of the secondary ﬂow is investigated, including the distribution of turbulent stresses. Secondly, the eﬀect of changing curvature on the degree of stratiﬁcation is analysed. Stratiﬁcation can be characterised by the friction Richardson number Ri_τ = (βgHΔΦ)/u^2_τ, and the bulk Richardson number Ri_b = (βgHΔΦ)/u^2_{bulk}. Here ΔΦ is the diﬀerence between the mean temperature at the top and bottom of the channel, u_τ the mean friction velocity on the solid surfaces bounding the channel, u_{bulk} the domain averaged streamwise velocity, β the volumetric coeﬃcient of expansion and g gravity. Stratiﬁcation can also be viewed in terms of the transfer of energy from mean ﬂow kinetic energy to potential energy via buoyancy ﬂuxes. We study the eﬀect of curvature on stratiﬁcation by investigating its eﬀect on the friction and bulk Richardson numbers, the global available, background, total potential energy, and the domain averaged kinetic energy. It is found that with the increase of curvature, Ri_τ and Ri_{bulk} decrease, while available potential energy increases due to increased overturning of the ﬂow, indicating that increasing curvature leads to a decrease in the level of stratiﬁcation.