A method of estimating a temperature of a component of a wind turbine, the method comprising: during a calibration period: receiving measurements of the temperature of the component measured by a temperature sensor of the wind turbine; receiving measurements of one or more operational parameters of the wind turbine corresponding to the measurements of the temperature, the one or more operational parameters comprising at least measurements of wind speed or power generated by the wind turbine; calculating, using the measurements of temperature and of the one or more operational parameters, coefficients of a model of the temperature of the component, wherein: the model relates a temperature of the component at a current time, T n, to a value of the one or more operational parameters at the current time and to a temperature of the component at a preceding time, T n-1; the model is segregated into separate bins based on wind speed or power generated by the wind turbine, such that the model comprises, for each bin, respective coefficients relating the temperature of the wind turbine at the current time, T n, to the value of the one or more operational parameters at the current time and to the temperature of the component at a preceding time, T n-1; and calculating coefficients of the model comprises assigning each measurement of the temperature and the one or more operational parameters to one or more bins of the model, and fitting the coefficients of each bin to the measurements assigned to that bin; and using the model to estimate a temperature of the component of the wind turbine. during a calibration period: receiving measurements of the temperature of the component measured by a temperature sensor of the wind turbine; receiving measurements of one or more operational parameters of the wind turbine corresponding to the measurements of the temperature, the one or more operational parameters comprising at least measurements of wind speed or power generated by the wind turbine; calculating, using the measurements of temperature and of the one or more operational parameters, coefficients of a model of the temperature of the component, wherein: the model relates a temperature of the component at a current time, T n, to a value of the one or more operational parameters at the current time and to a temperature of the component at a preceding time, T n-1; the model is segregated into separate bins based on wind speed or power generated by the wind turbine, such that the model comprises, for each bin, respective coefficients relating the temperature of the wind turbine at the current time, T n, to the value of the one or more operational parameters at the current time and to the temperature of the component at a preceding time, T n-1; and calculating coefficients of the model comprises assigning each measurement of the temperature and the one or more operational parameters to one or more bins of the model, and fitting the coefficients of each bin to the measurements assigned to that bin; and receiving measurements of the temperature of the component measured by a temperature sensor of the wind turbine; receiving measurements of one or more operational parameters of the wind turbine corresponding to the measurements of the temperature, the one or more operational parameters comprising at least measurements of wind speed or power generated by the wind turbine; calculating, using the measurements of temperature and of the one or more operational parameters, coefficients of a model of the temperature of the component, wherein: the model relates a temperature of the component at a current time, T n, to a value of the one or more operational parameters at the current time and to a temperature of the component at a preceding time, T n-1; the model is segregated into separate bins based on wind speed or power generated by the wind turbine, such that the model comprises, for each bin, respective coefficients relating the temperature of the wind turbine at the current time, T n, to the value of the one or more operational parameters at the current time and to the temperature of the component at a preceding time, T n-1; and calculating coefficients of the model comprises assigning each measurement of the temperature and the one or more operational parameters to one or more bins of the model, and fitting the coefficients of each bin to the measurements assigned to that bin; and the model relates a temperature of the component at a current time, T n, to a value of the one or more operational parameters at the current time and to a temperature of the component at a preceding time, T n-1; the model is segregated into separate bins based on wind speed or power generated by the wind turbine, such that the model comprises, for each bin, respective coefficients relating the temperature of the wind turbine at the current time, T n, to the value of the one or more operational parameters at the current time and to the temperature of the component at a preceding time, T n-1; and calculating coefficients of the model comprises assigning each measurement of the temperature and the one or more operational parameters to one or more bins of the model, and fitting the coefficients of each bin to the measurements assigned to that bin; and using the model to estimate a temperature of the component of the wind turbine.