I’ve seen numerous formulas for calculating wind drift in the field, none of which are any good when your brain is boiling prior to a shot. The only workable one comes from my friend and colleague Wayne van Zwoll. According to Wayne, if you’re shooting 180-grain .30/06 bullets at 2,700 fps, and the wind is coming at 10 mph from a right angle, allow 1 inch at 100 yards, 2 inches at 200, 6 inches at 300, and 12 inches at 400. If the wind is coming from 45 degrees instead of 90, you halve these allowances. If it’s blowing 20 mph, you double them.
Watch the wind out where the animal is. The wind where you are is not going to have much effect on the bullet. The most important thing is to practice shooting in the wind. A couple of years ago, I was shooting a .308 at 600 yards in South Dakota and being coached by a former member of the Marine Corps rifle team. He was giving me very accurate wind adjustments out of his head, and I asked him how the hell he did it. “Easy,” he said. “You watch ten or twenty thousand 7.62 bullets go downrange and you get to know just what the wind will do. If it were another cartridge I wouldn’t have a clue.”