When you reach Zone 3, you will be introduced to the Wind feature. This feature makes it so you have to alter your aim on the target depending on how windy it is. The strength of the wind is indicated at the bottom-left or bottom-right corner of the screen (depending on which direction the wind is blowing). You should also see a range of numbers on the left of the reticle when you zoom in. You will need to align the target to the correct wind strength using the numbers on the left of the reticle as your guide.
Note at this point that the Distance feature will also be in effect so ensure that you alter the aim based on Distance and Wind.
Also, in later Campaign missions, the wind can change in value and direction.
This feature is only available in Campaign and certain PvP missions.