Asymptotic approximations to the zeros of Jacobi polynomials are given, with methods to obtain the coefficients in the expansions. These approximations can be used as standalone methods for the non-iterative computation of the nodes of Gauss--Jacobi quadratures of high degree (n≥100). We also provide asymptotic approximations for functions related to the first order derivative of Jacobi polynomials which can be used to compute the weights of the Gauss--Jacobi quadrature. The performance of the asymptotic approximations is illustrated with numerical examples.