Thermal regimes of seasonally ice-covered lakes in an arid region like Central Asia are not well constrained despite the unique climate. We observed annual and seasonal dynamics of thermal stratification and energetics in a shallow arid-region lake. Strong penetrated solar radiation and high water-to-ice heat flux are the predominant components in water heat balance. The under-ice stratification and convection are jointly governed by the radiative penetration and salt rejection during freezing.