If the ballistic app is telling you 3.something, and you are at max magnification, then yes.
Gauging wind strength is one of the hardest things to do. Even with a wind meter like a kestrel, you only get it at the location.
Have a look at Thomas Haugland on Youtube (Norway on here), he had some good wind estimation techniques (in m/second) looking at vegetation. Terrain can have a massive impact, if you are shooting over a gully, the flight path is normally in faster wind than what you see at ground level.
In very rough terms 1 m/s is about 2 mph
Easiest way is to have a decent backdrop, and lots of people looking for the shot fall. Then use your reticle to measure the size of the correction and apply it. Having a brake etc on the rifle helps a lot with seeing shot fall.
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