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The transition metal oxides MnO, FeO, NiO, and CoO are essential materials systems for catalysis applications and energy technologies. These materials exhibit a magnetic phase transition from paramagnetism to antiferromagnetism upon cooling. In this work, we show that an accurate treatment of the surfaces requires a description of the disordered local magnetic moments of the paramagnetic phase. We determine how the magnetic phase transition and the presence of solvent affect the surface energies using density-functional theory and a solvation model. To accurately account for the correlations in the d-electron system, and to match the observed magnetic order and band gaps of the room-temperature phases, we include the Hubbard-U correction. In the case of MnO, FeO, and CoO, which are paramagnetic semiconductors or insulators at room temperature, we demonstrate the importance of the local …