This study extends the research on atmospheric conditions and scoring in sporting events by examining components of air density as it relates to National Football League (NFL) games. Statistically significant results were found in relation to the role of humidity in explaining the difference between actual scoring and the betting market total for NFL games. Simple wagering strategies based on humidity, wind speed, and a combination of these factors were shown to reject market efficiency. From game statistics, it appears that humidity may unexpectedly influence the rushing game, leading to greater than expected scoring when humidity is high.