Yes, WINDAGES is a Scrabble word!

Letter values in Scrabble US: W 4, I 1, N 1, D 2, A 1, G 2, E 1, S 1.

Is it a valid word?

WINDAGES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the retarding force of air friction on a moving object
the space between the projectile of a smoothbore gun and the surface of the bore of the gun
exposure to the wind (as the exposed part of a vessel's hull which is responsible for wind resistance)
the deflection of a projectile resulting from the effects of wind

Also: wind exposure, wind deflection.