The weather is becoming windy again. The Great Plains is a windy place, but during summer, and July and August in particular, average daily wind speeds drop nicely. Many days are relatively calm and even the windy days in high summer are not particularly windy. Thunderstorms provide an occasional exception, but thunderstorm winds rarely last more than a few minutes. The reason for the increase in average wind speed during the colder weather months is not directly related to temperature, but to the difference in temperature between the polar and equatorial regions.
In summer, this difference is relatively small, which causes weaker weather systems. During fall, winter and spring, it gets extremely cold across the polar region while the tropics remain tropical. This enhanced temperature gradient leads to a stronger Jet Stream and larger air pressure differences between weather systems, both of which lead to more wind in general.