If you launch the projectile with “Add Impulse”, then once it is launched, you add a force with “Add Force” every tick. It might be better to disable the standard gravity altogether and even just use velocity change and not take mass into account.
You just make a vector perpendicular to one axis, wind velocity on another, add them together, and put it on the add force. You can do it without gravity by adjusting the wind’s direction, but it’s not really the point - the point is, you add to the current velocity every tick once the projectile has been launched.