Curved steel box girder bridges have been increasingly used in practice due to their distinctive structural merits. However, compared to straight configurations, their geometry may induce significant torsion and coupled bending-torsion effects. Under large ambient temperature variations, they can also be susceptible to considerable temperature gradients and complex thermal stresses, leading to the temperature fields with intricate spatiotemporal characteristics. To this end, this paper investigates the temperature field distributions and associated mechanical response of curved steel box girder bridges through field monitoring and finite element analysis. Based on the field measurements carried on a representative case study bridge, the vertical and transverse temperature gradient models are proposed for curved steel box girder bridges. It is shown that the vertical temperature gradient can be closely characterized by an exponential function, whereas the transverse temperature gradient closely follows a Gaussian distribution. The proposed temperature gradient models are subsequently applied to derive the vertical and transverse temperature differences for the curved steel box girder bridges located in 12 major cities across various climatic zones in China. The resulting temperature field distributions and thermal-induced mechanical responses, including thermal stresses and deformations under individual as well as coupled vertical and transverse temperature gradients are assessed in detail. Particular focus is given to examining the influence of the curvature radius on the thermally induced deformations, stresses, and torsional behavior of curved steel box girder bridges. The findings provide a fundamental basis for improving the design procedures and offer systematic region-specific thermal loading parameters in support of climate-adaptive design approaches for curved steel box girder bridges.