This paper presents an optimal guidance approach for a UAV point-to-point navigation in 2D, under wind perturbation, with a general desired airspeed profile. A cost function weighting the travel time and the control effort is minimized through the Pontryagin's Minimum Principle, involving the derivatives of the airspeed velocities. Two iterative procedures for a guidance algorithm under general wind fields were developed, including an analytical solution for the optimal heading in minimum-time paths. Different cases from the literature are compared and a hard wind scenario test is presented.