Choosing wind is the option in which a team decides which end of the field they would like to defend first. Regardless of which side they choose, the teams switch defending end zones at the end of the 1st and 3rd quarters.
Wind and weather have a major effect on football games, especially since most stadiums are outdoor. The wind direction has a major impact on passing, and more importantly, kicking and punting. A team can strategically choose which direction of the field they'd like to defend during the game or in overtime if there is projected to be heavy winds, so in case of a game-winning field goal, the kicker will have help from the wind. If the kicker is kicking with the wind, it will carry the ball further. If he is kicking against it, it is much harder to kick the ball far. The wind and weather can also have a major effect on punts, making them fly longer or shorter similar to kicks. The weather can also make the ball bounce more off a punt.
If a team is going to choose which direction to go in, they will always choose to go with the wind. It allows the quarterback to pass the ball further and kick the ball with more ease.