I dunno dude, Dallas gets pretty hot in the summertime. Any day game, I'd say, at least has a small shot at the title.
While I am reviving an old post, I think if you take this study a step beyond weather, you can come up with some sort of ballpark effect, similar to baseball. I know different stadiums have different effects to how players are tired depending on the elevation as well as the ball traveling further, minor effects from the field have slight variations as slanted fields, wind effects, games played during the night or day. While I am not sure if a study of this can be effectively calculated, is anybody aware of this being done?
This is very interesting. I know there are several academic papers which examine the effect of weather on attendance at sporting events. In England they find the colder/worse the weather, the higher the attendance. In North America they find the colder/worse the weather, the lower the attendance. I'd be curious to see whether the North America effect changes when examining soccer.