score:5
Wind affects how long a flight takes.
A jet plane travels at about 550 miles per hour. If you have a 100 mph head wind then your speed overland is around 450 miles per hour. If you have a 100 mph tail wind than your speed over land is about 650 miles per hour. Over the course of a 3600 mile or longer flight (about 6.5 hours without wind) the difference can be quite noticeable.
Furthermore, wind patterns can be seasonal. There are some flights that take 6 hours during part of the year and 9 hours during other parts of the year.